Here's what I've got:
1983 Eliminator Formula 19.5' day cruiser with a Berk 12JC pump, place diverter, AA impeller, Hardin Marine 460, Hardin logs/snails.  D3VE(smog) heads, D1VE block(2-bolt main), and -10/-10 crankshaft. I'm not sure what cam is in it- previous owner had no clue either.

Long story short, my starter bolts were stretched and eventually ate some teeth on the flex plate.  The motor is out and apart, down to the block- but the heads are still on.  Crankshaft is out, but pistons/con rods are still in. I was planning on pulling the heads and porting out the 'smog hump' in the exhaust chamber for more flow this winter- but I wanted to get some input from you guys first. 

The boat is a slug out of the hole, but the place diverter helps as a band-aid.  My question is; what pistons do I need to look for to increase my compression and pick up more HP?  I know that going with O/T exhaust would help- but I don't want to go that route.  Also- I want to keep the same marine crankshaft that I have now. Dish/domed/valve reliefs?  Help!

Updating this:  I pulled the heads off last night, and measured the cylinders.  The bores measures 4.5299-4.5304 with a 3-point ID mic.  That makes them .170 overbored.  Everything I'm reading, and people are saying is that the block is trash. 

Holy crap! By your dimensions, and a 3.85 stroke, that's a 496 cube motor.

Lakes only is the Ford big block guru.

The 'dog out of the hole' is likely in the pump. Wear ring to impeller clearance.

My junk, 454 with a 'AA' American Turbine impeller, was night and day difference over a Berk 2A worn impeller (Thanks Tom!)

Your 460, should easily put out 500 hp, about the hp or more to pull that large of a wheel. Mine went to 4950-5K, about 505 hp by the impeller charts. (Thru logs and snails)

Sourcing a std. bore 460 block and camming it accordingly, keeping comprehension at 9.5 or so should be able to get to 500 hp or so. The heads might hold you back some.

What were you able to run as far as rpm with the old set-up?

On dual plane manifolds, I run a 1" spacer, helps with top end. I prefer single plane manifolds for jet applications.

Hope this helps.
Dan'l

I'm an idiot and got the wrong measurements with a 3-point mic.  Went back and measured it using a dial bore gage, and got WAY better numbers.  The actual bore is 4.390, .030 over.  Verified after cleaning the pistons up. 

Now I'm on the fence about going with T/T headers, or capping the transom and putting O/T headers on....