The 2871 w/ 64 small exhaust back housing + poncam 256
for almost 20 years ,
Ideal 350rwhp range for stock bottom end sr20det (92-02) for novices
You can push 2871 to 400 Ive even see 420-450rwhp but it takes alot more experience and careful considerations, tuning, heat control, etc... (It costs more and there is more chance to make a mistake) for the extra 50~ hp.
I recommend sticking near 350 until you become a master of tuning sr20det engines then try the 400~ range on a T25unit if thats still your idea of a good time
Top mount varieties are generally superior in almost every way except cost. It can spool superior, make more power, control heat better, easier access, everything gets better. Even the turbo can be reduced to 1/3 cost (brand new Borg Warner unit IMO). However the placement and fabrication aspects, combined with required knowledge of bracing and flexibility in the plumbing (so nothing will crack) and vibration damping make it a difficult job and may lead to breakage and leaking if the owner/installer is not familiar with all of that setup involved. It can also be difficult to find a top mount manifold which has good access to certain parts (a/c stuff, wastegate positioning, turbo feed lines access, bolt tightening access, etc... can be dicey on a LOT of versions)
other thoughts:
once we pass the ~440rwhp barrier an old 2.0L is stretched a bit thin in a daily driver situation (If thats your goal)
I recommend for up to 400rwhp the 2.0L Is a great engine
For 450-650rwhp I recommend the 3.0L 2jz-gte (daily drivers around 3000lbs its great)
And for 650-1000rwhp use the L33 Engine (5.3L From 2005-2007 Silverado)
All of those engines can keep OEM stock bottom ends so there is no down time, no machine work, etc... And they are all similar priced and will easily go 200,000 miles with the stated power in capable hands