Its a KIT CAR, so really anything is possible.

As long as its safe and more importantly looks "right" then its all good.

As for the roll cage, id personally remove it and make a complete new one to size, so it didnt look like an add-on. Tho I guess it depends how much you want to spend.

Im 6'4" so know how uncomfortable most cars are. Dont think ive found a car yet where everything is ergomomic the taller driver.