As far as replacement sensors -
Most every aftermarket system I have investigated standardized on GM-type sensors, meaning the sensor resistance curves are comparable to what GM used. There are a plethora of variations in the aftermarket regarding wiring connectors, mounting threads, etc, but if you're needing a replacemnt part ASAP you'll probably be able to get something that would work, or could be rigged in temporarily, at a parts store. Looking at a part for a 1990 GM __________ is a good starting point.

And for any home-brewed JY EFI system, unless you get it all for free you better plan on spending at least $500 minimum. A new 45 PSI pump will run $80 minimum, fuel lines and fittings aren't free, you'll want new sensors ($50 easily) - it adds up quick. A junkyard ECU will be $50 minimum, too.

And there's a TON of info and upgrade parts out there for the GM TBI system, and even though TBI is frowned upon it still offers lots of benefit over a carb.

OK, sidetrack over...