I'll be doing a minimal bore, most likely (hey, 212k miles will wear on any engine out there) so I'll most likely be cruising on an 83.5mm bore. Not enough, imho, that the increase in displacement is worth it.
The stroke of the 7M is actually just a bit more than I would like in relation to the bore - but then, a 3.582" stroke, is still a small stroke in relation to what I'm used to (400 Poncho with a 3.75, or a 455 with a massive 4.21" @ 6500rpm!)
Actually, Nick, now that I think about it - you may be right about power output increase. Lighter rotating assembly = less work needed to spin it. A small bump in compression, and optimized quench will give me more power per unit fuel. Crank scraper + knife edged crank will reduce windage in the crankcase, freeing up more power.
I suppose the more accurate thing to say, would be that I won't be making more power - just freeing up power that was already there!