Due to the age of the engine, are you thinking about using a slightly thicker oil? I know a lot of people tend to do that on higher mileage cars to help compensate for the loosening of tolerances due to wear and tear. I hear both the 4A-GE and the 4A-GZE are pretty tuner friendly. Are you tempted on modifying the engine much?
I've never had oil pressure issues with this engine (except when cornering hard at speed, but that's because I need to baffle the sump if I'm going to drive it like a racecar). I'm actually not sure how many miles the engine has; the chassis has ~210k miles but the engine was swapped at some point, so all I know is that the engine has more than 30k miles on it. I am very tempted! Now that I have a second supercharged MR2 that most likely needs an engine rebuild, I will save my modding for that car first. This one might eventually get a 20 valve 4age or something else down the road, but that'll be after I graduate. Toyota makes a couple of other engines that are worth swapping in, or I hear that doing an H or F series Honda swap isn't that bad either.
Honda engines sound pretty reasonable actually. I've been to import events where I've seen Civics and Preludes run high 11s and low 12s so they definitely have some room for modification. Seeing as how pretty much all of their engines are for a transverse setup, it'd probably be a relatively easy install. Though I figure, hopping up the current engines would be cheaper and easier if they're in good shape.