The sr20 is an engine that runs an alloy block with no liners and rockers in the head,it wouldn't be my first choice for a high powered car tbh.That said,I have 1 and I can get all the parts to make it quick fairly cheap so I'm considering it.
I'll probably use a head off a Sunny gtir to make it rev though.
The ca18det revs more easily and has a much stronger block if you build it properly and sort the oil surge problems.
I can see where you are coming from with the 1jz and a friend of mine has 1 for sale but it comes with a free soarer.The 1jz would be a lot more hastle to do and would cost more in the end I reckon.
Get an s12 and if you want to I reckon you could fit a Toyota engine under the bonnet if you tried.
Or you could go with an rb26
