change the timing chain to a 1970 model tru roller, small 500 lift cam, and rpm intake and you have over 400hp really cheapThe factory 460 marine cam specs are already at .500 lift.
The M-6250-A460 Hydraulic Flat Tappet Cam = 0.493" Intake, 0.502" Exhaust and 216°@.050" Intake, 220°@.050 Exhaust.
These factory 460 marine engines benefit greatly from head porting and a compression ratio increase (if you have the dished pistons). A real popular swap for our customers is to R&R the D3VE heads for ported D0VE heads with 1.8 ratio roller rockers...100HP gain is possible even when keeping the thru transom exhaust.
LO