I have not been here in awhile, and this thread has gone OT quite a bit.
1) Nice oil pan idea, but have you actually fit that in the car yet? The area is not very wide actually, so measure twice, and cuss less.
2) Scrapers as noted need to be fitted to work well. Also shimming the pan down, and using a gasket as noted = leaks. (I reccomend never use a gasket on the oil pan, just use well placed form a gasket, or right stuff for no leaks.)
3) The idea of removing guide pins, and plugging up oil holes in the pump? WTF? Easy pump mod. Shim the pump bypass with one 10mm nut. Done. If you want more flow, ARZ's hard pipe upgrade appears to be a great option.
4) Squirters are a source of "lost" oil pressure, but Toyota did put them on the engine for a reason. Cooling your pistons is no joke, so keep them on the engine. Coatings are not a bad idea either for the pistons. The stock rod "squirter" hole in the shoulder sprays oil on the piston bore thrust surface. I'd think that over many years of use, not having them would just about balance out the possible rod bearing wear avoided by keeping more oil pressure on the rod bearings v/s lubing up the walls of your bores.
5) The best pan upgrade I've seen yet is kicking out the side where the pickup is up against the pan. Then adding a Group A type round baffle with slots cut into it that goes around the pickup basket. Also bending the pickup basket down so it's deeper into the oil in your pan. (Simple measurement here, but it's too high off the pan floor stock, and that is all oil you might need someday.)
6) Scrap your pressure based cooling system. Get a remote filter, cooler and use a thermostat. You want your oil hotter than 180f, but cooler than 220f. Thermostat and a large cooler with do that. Anything else, and your just guessing it's right.
7) Buy good filters. Canton/Mecca is not a bad choice. There are others too. Don't spend 500.00+ on this and then spin on Fram shit box filters. It makes those of us who care, weep. Purolator, Wix and Champion all make good spin on filters. (Yes, Champion, who makes the WalMart ST filters by the way, so you do not have to spend lots, to get quality actually. Just research, and there is TONS of info on filters out there.)
8) If you are going to slide, brake or drag your Supra, I highly reccomend a accusump type device. You prelube your engine before start up, and you protect it all the rest of the time from low pressure. It is cheaper than an engine rebuild, or trying to figure out a dry sump setup. The only downside is finding space for the sump, and paying for the pumbing.
9) Last, run more oil. 1 quart on a stock engine is where you should be on the LOW end. I've run 12 on my setup, but find that 10 appears to be perfect. No blowing oil out the dipstick at the drag races... My crank is knife edged, I do not have a scraper, I did not modify my pan, but my engine is always sitting on 3 quarts of reserve oil ready to be forced into it if the pressure drops below 20lbs at any time while running. I've found on my engine, that "Full" is when the oil level is just at the wire on the dipstick. (Where the flat metal is crimped to the wire... that's the full point.) The crank/rods even on my stroker engine are nowhere near the oil in the pan at that fill level. With the stock pan, you are going to have sloshing oil even with 5 quarts, so why worry about running 6 or 7? BFD for the few seconds of windage loss, v/s a possible rod knock or other bearing damage? The other hours of use, your engine will not be whipping up any of the extra oil.
Just my observations.
PS: Hear this "Oil drainback holes... blah blah, and how oil could be trapped up in the engine/head.." And that oil is trapped on one side of the head or the other.........Anyone who says that and has actually looked at a 7M head apart must be blind....... You could pour GALLONS of oil through a 7M drain back system. And unlike some other heads, the 7M design can't trap oil on one side or the other.. Just look at it, and you will quickly see what I'm talking about.