both ls and b20 are 89mm Homie, gsr is 87.2mm.. 220hp is much easier with a b20, only because it has a 84mm bore... Sleeve an Ls block and go 84/85 and you will have the same result if not better...
My race motor would look like this; Sleeved ls/vtec or b20/v, if that's what you have!!
86x89mm 14:2 w/E85
Wiseco Pistons
Carrillo A beam rod
PortFlow head(GSR) and pro3's
BMC or Magnus intake
TODA or Hytech header
1000cc injectors
Many combos to run though, for street I would do this;
84x89mm 12:5 to 1 on 93
wisco/CP depends on budget..
any h beam rod, eagle, BC, etc.. Unless you got money for the light rod!!
Stock GSR head or ported if you can afford it
Ported ITR, shunk2 or AEBS intake
Pro2's or 3's
Hytech or Toda header
450/550cc injectors
Each to their own, but just listing my 2cents, no pun!!