I note you didn't post the link to that ad. Must mean you really want this one
Go for it! It's the nicer body style, though 150-200 lbs heavier than the ForkenSwift shell.
Synchros... it's more of an issue if you go for a clutchless connection, because you rely entirely on the synchros to permit you to shift.
That said, I'd also bet money that this car has the wrong weight (too heavy) of oil in the transaxle, and going to a lighter oil will help some.
Also, if you do a 72v conversion, you can just leave it in 2nd gear for the vast majority of your driving. 48v/225A isn't powerful enough to get away with that.
Another plus, the last gen Metros had ridic ground clearance. If you stick 600 lbs of batteries in them, it won't be scraping the pavement like some other small cars will.