Be careful with adding roach to the main alone. This WILL move the centre or aerodynamic pressure further aft which will affect the balance of the boat. It will tend to point up more.
You'd need to do something similar to your normal Jib
sail, more overlap?
My Prout CAT has a battened main with a big roach, I'm sure it has unbalanced the boat a good bit, or it could be poor sail trimming!
From many threads the folding prop is very cost effective, a clean bottom is next, your labour is cheap
. But if you are going to replace the standing rigging
and sails, well that's the time to make the decision AFTER getting the costs for design, build and install.
It does bring an older boat up to modern standards of performance but the old skipper
has to be aware of a more tender
boat. For a cruiser an old proven boat with a better 24hr range is useful, if you're pottering along, coast hopping, then run the engine
a bit more, with a manually (hydraulic) adjustable pitch
prop that feathers. Low revs when sailing in light winds keeps the speed up making sure you arrive before dark etc..