You'll need to swap distributors for a passenger car/truck type with a vacuum advance, or the gas mileage will be lousy. Im general, the Mercruiser engine will be somewhat of a hotrod, with a more radical cam and higher compression, so running midgrade fuel would be a good idea. I think some of them ran a 2-barrel carburetor, which would also boost the high speed performance a little. You'll encounter a slightly choppy idle from the cam upgrade, so a standard transmission or a higher stall speed converter if you run an automatic trans would be advisable to prevent bogging down at low speed.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
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