The fastest 305's were in the Monte ss's & they only got 185hp, best option is always to go for a 350 swap
a 350 will produce around 250 hp, and a 305 about 200 hp
The 305 "HO" was actually dropped after 1986. In '87, the base 305 TBI was rated at 170 hp, the 305 TPI was rated at 215 hp.
305 HP @ 5,200 rpm
305 hp
180hp
Base 305 4bbl (170 hp), optional 305 TPI (215 hp) or 350 TPI (225 hp)
1989 was 160 hp 1998.5 was 215 hp 2003 was 305 hp
305 hp
305 hp
305 hp
305 rwhp
about 165 hp