just recently my car passed 130.000miles , so im just trying to bring her back alive ...

i drive this car everyday in wilmington and ive notice the compression and torque have dropped a lot in the past 6 months so i got new valve seals ,p/p the head ,
and a few more things , but the block needs some work so im just wanna upgraded it to a b20

my car its not really highly modified but this is what she has...
3< valve job
port &polish
mugen valve seals
type r intake manifold
dc headers
2.5 inch exhaust
stage 2 exedy clucth
cold air intake
a/f meter APEX'i
tenzo-r cold air intake and tach !

my problem is that i need to get another block and tranny that will be able to handle the stress for my dayly and weekend car
im not really aware about the diff between b20 and b20z? or if i should go w ls block?

ps: how much should i be running in the 1/4 w these mods ?
if i have 17 inch and the car is striped from the front seats back?
what other mods will be highly recomended?

and if someone knows about how much NOS could i be using? Never used it , I got it from a friend that owed me money . not really NOS fan


thank for your time