what next ...please HELP

ok her it is i have a rude 1970 85/h/p .well i have had proublems with the lower unit,fixed. proublems with wireing,fixed. proublems with the carbs,fixed.no i have a new proublen {what next} the other day wile on the lake my motor lost power and i shut her down.then i took the cover off to discover that my motor was smoking . ok so i got towed in and took her home when i took off the lower unit i found that the impeller was no good .i had put in a new impeller and re assembled.now i know that i should replace head gasket "per whit i have read" but do i have to do that before i check compreshion. and also it seams like i dont have any juice from the battery but it was just bought today. motor turns fine bye hand not frose up cylenders look fine through plug holes.. any help will do {WHAT NEXT}

Re: what next ...please HELP

1st - Tighten every bolt on that engine as they're no doubt loose if it ran that hot. The head bolts must be torqued properly in a specific sequence. Seer you service manual.

2nd - With the engine not running but with the key in the on position, find the TAN (overheat sensor) wire protruding from the cylinder head and grouns it to the block. The warning horn or most likely in your case the overheat light should come on. If it does not, find out why as that's the only warning you'll receive when the engine starts to overheat.