SN1FTR lives! After draining then dropping out the fuel tank I pulled the pump out. A quick visit to PickAPart confirmed that a 20V pump (or just about any Toyota pump judging from the 3 different Toyotas I looked at) will physically fit in the bracket with a little persuasion. Problem is that the 20V pump has a nice plastic connector for the pump wiring and the AE82 just has round terminal ends that bolt onto the pump. Easy enough to cut the connector off and crimp on the right terminals but I also noticed the 20V pump has some kind of resistor(?) wired into the works, the AE82 doesnt have this. Rather than install it/not install it and have issues later (pulling the tank out is not pleasant) I bought a pump of FXGT Race that I knew would fit. So fitted the new high flow pump and put everything back together...fired her up and blew a hole in one of the high pressure fuel lines that had a hairline crack in it. Fixed that...ALL GOOD, runs like a dream! Infact it has quite a bit more midrange torque but thats probably from resetting the timing.
So thanks to everyone for your help, its been much appreciated. I'll chalk this one down to experience and not owning a fuel pressure gauge. =)