Need help with new engine

I have a 1990 prelude si B21. i wanted some advice on what to do with it. i threw my number two rod bearing. i have since pulled the engine and cleaned and inspected all parts. Crank is junk, all rod bearings are worn. head is in very good shape i port on polished it just since i had some spare time. block seems to be excellent shape besides the stupid FRM cylinders! i want to know if i should rebuild it. buy a used one or go with the JDM B20A5:) I wanted to know how performance wise the B20 compares to the B21 i know the B21 has slightly more crank power than the B20. So if i did go w the B20 how could i get some more power besides the basic port and polish and valve job. CAI and Header. I plan on replacing all seals and gaskets just to have some cheap insurance. If anyone has a B20 or B21 give me a heads up.