Ls vtec is the way to go under strict circumstances -

forged rods and pistons
arp rod bolts
gsr block girdle (not necessary but i have found it makes the engine run smoother)

and as for b20 vtec its pointless just becuase the sleeves are to thin if u want b20 vtec simply buy a ls block and sleeve it so u can bore it too 84 or even more than 84 with the right sleeves .

yes understandbly this shit cost alot of bread . cheapest and easiest way u want to know ? put a gsr girdle and arp rod bolts on the short block and nothing over 8k tho but it is very dependable , also type r oil and water pumps

but LS VTEC any day of the week man FUCK b20 vtec