Thanks for the info SS.
As far as i have seen the water outlet is the same on both the only difference is the width of the intake the 351 is taller due to its longer stroke making the valve covers farther apart This would also make the exhausts higher and wider that might explain the turn down humps and additional plumbing most of the HM humps I have seen in I/o classics are straight end dumps
It very well could be a 302. Just curious about the scoop I had a HM 351w in a 16 without a scoop. Don had a 302 in the same 18 without a scoop
Either way still looks like a nice boat