If you have much body work to do invest in a rotisserie then sell it afterwards. Made mine so much easier, and better. I had to replace the lower quarters and weld patches in a lot of the rocker areas and it was huge. Helps you not have to be a contortionist.
I find the 1147 is just fine. You can't use more power in the water generally due to propellor cavitation and on the road the 1147 gets you up to 60 which is as fast as I'm comfortable driving it as twitchy as the handling is. Yeah you slow for hills, but I live in the Rockies and if I'm going somewhere far away I just trailer it. There are issues with using a 1500 so be sure and talk to people if you are thinking of going that way. John Friese has done several, I think both of his cars are upgraded. I'd be worried about the tranny, they are somewhat fragile.