I assume you're in Oz or NZ?
if not disregard,
Pride made a number of 13 ft hulls between the 60's and 80's,
13ft hulls have narrow beams, a fair bit less than say a 15ft boat,
depending on brand there will be around 20 kgs difference between your 60hp and a 35 hp merc etc
there's quite a few 13ft pride boats on gumtree with 20- 40 hp outboards on them...didn't see any with a 60hp,
l think a 60 hp chrysler is in the low 80 kg range though yours does not appear to have power T&T
can't easily change the trim on the water to help with your water over the stern problem,
Not getting any better news now,
sorry but the magnapower 11 IGNITION system was bad from new and was recalled by chrysler and replaced....not all were in Oz...new ignition parts for both the 60 and 120 ( we had that one 10? yrs ago, same system ) are NLA
it took us a LOOONG time to find someone in NSW that had 2nd hand modules on hand,
Hope you don't need them but the donk is from the 70's,