Thanks for the responses. I can see how the manual is very cautious about having any mineral or petroleum solvents touch the timing belt, and perhaps it was written at a time when there wasn't much selection of water based degreasers, but I don't see the problem using a water based product on the camshaft pulleys. The goal with such cleaners is to leave behind absolutely no residue of any sort, just squeaky clean metal, which can't be a bad thing. I do see how you should avoid cleaning the tensioner and idler pulleys as I expect that they are internally lubricated with oil and we don't want to wash that away.
I plan to install a brand new Mazda timing belt.
I do not plan to clean off the piston tops, and my concern about contaminating the oil is only about the residue that I will clean off the top of the block, which I'm hoping to do with chemicals, not abrasives. I am doing this work with the engine in the car, and only have two weeks to complete it before the next race, so getting the oil pan off is not in the plan. I'm definitely overthinking everything and am paranoid, as you would expect from a beginner. A mechanic (an SM expert) that I can talk to occasionally, thinks that I should be fine with vacuuming/blowing any particles out of the cylinders with compressed air, followed by a wipedown of the cylinder walls along with an inspection to look for anything that may be scratching the walls. I'm going to do that. Then I'll put rags into the cylinders for the remainder of the cleaning.
I'm following the factory manual for the most part and cross referencing to a Grainger Miata manual. The factory manual is pretty clear.
My biggest concern is the fact that I don't really know for sure why the gasket let go. This was the first race weekend on a known-good engine donated from a used street miata, that I just got installed in my car. The only thing I did after the install was to replace the thermostat with a 160 deg new unit which I tested first. There is a possibility that I didn't do a good enough job getting air out of the cooling system, but I think I burped it correctly. The moment the gasket let go on the track I looked at my temperature gauge and it read just below 210 deg. It was the hottest day of the year (which in my neighborhood means 90 deg air temperature), we were about 10 minutes into the race, I was pushing the car pretty hard and had spent about two laps drafting a Honda Civic pretty closely.
Because of this concern, I'm looking at all aspects of my cooling system. I've flushed out the radiator which is an FPS race rad, will be bypassing the heater core and will be using 100% water with a bottle of wetter added. I will flush the cooling system as much as I can prior to closing it up for the next race, and am filling the system with the vacuum fill method (ie. Airlift). The water pump seems to be fine as far as I can tell (turning easily, no slop or play).
I will not be re-using the head from my engine. Instead I've got another head that I then had rebuilt at a good shop (machined flat, valves ground, new retainers, springs checked and replaced as needed, camshaft bores cleaned etc). This should take car of the concerns about warpage or other head damage. Haven't checked the block deck yet, but will give it a look with what straightedges I have on hand.
I tried to put pieces of regular masking tape on the block's oil holes before starting cleaning, but the tape doesn't stick to the oily surface. So I will try to use some cotton rags to close the holes.
I'm interested in the Mazda racer program and will look into that. Not sure if it applies to us Canucks but in any case I am already a believer in Mazda OEM parts.
I've got another question. The factory manual (and many online experts) instructions call for the removal of the head plus intake manifold as a single unit, so that's what I did. So, since I'm fitting a new head, I have to move parts over from the old head+manifold assembly to the new head. Should I do all of that before installing the head back on the block, or should I put the head on the block first followed by the cams and the intake manifold? Fitting everything to the head before installing it makes it pretty heavy and awkward to handle but I guess it removes the difficulty of how to get the intake manifold fasteners back in. What do you think?