First question, raise the front of the car as high as you can and drop the unit of a trolley jack. Split the engine and gearbox once it's on the ground. I used to be able to do an engine change in one day working myself with just axle stands and a trolley jack.
Fitted a 1.7 8V to my Sud many years ago. It had the following done to it:-
Bottom end lightened and balanced.
Inlet manifolds matched to heads.
Valves de-shrouded and 3 angled.
Up-rated valve springs.
Deck height reduced to increase compression ratio.
Trumpets with socks.
The guy who built my engine (was based in a small unit on an airfield somewhere near Gloucester, can't remember his or the companies name) reckoned the standard cam could generate 140 BHP if the engine was breathing correctly. If you wanted more, you then went into pocketing the pistons to allow bigger valves and more aggresive cams.
I never really got the best out of the engine because it was running with a 1.5 QV manifold as I still had inboard discs (which prevent the fitting of a 1.7 QV manifold).
Engine was mated to a 1.5 QV gearbox (shorter ratios than a 1.7) and was extremelly rapid through the gears. Mid-range grunt was awesome. Induction noise was addictive. Never had a working speedo the whole time I had the car, but I once saw 7K RPM in top!