Will be doin a swap soon

Ok I have a 94 Ls with close to 150k on it. The motor is still quite strong and everything, but i know that wont last for a long time. I want to know how much work it is to swap in a new engine, and sum good suggestions on what engine to put in: b20,b18c....?

Gsr swap would be nice but for more Hp and maybe little less money you can rebuild your motor with a b16 head on it.or a b20 with vtec head whichever one would be nice..

i just want a direct replacement. which is faster stock a b20 or b18c?