Hello James - first question is what you are doing emailing at 1.16a.m? Is the issue costing you sleepless nights?
I am jsut on the point of putting some Seagulls on ebay to slim my collection, and have a nice Featherweight to go - rebuilt by me a few years ago with rechromed drive tube and exhaust but has the later cord pulley on it - not a problem unless you are concerned with originality, and I might be able to find a correct set.
I believe this would be the correct size for your boat - I also have two nice Forty Pluses to go, which I think would be too large.
The Featherweights were supposedly 2HP, but it is generally acknowledged that 1HP is more realistic.
I hadn't run my Featherweight for some time, but in preparation to selling it I ran it last week, and it starts,runs, cools perfectly well.
Email me on email@example.com
if you are interested - I live (survive) in Huntingdon. Rick