regarding the Vi, well this is probably the best route to go for the Rover K series engine option. It is a Rover 200 with the 1.8 VVC (variable valve control) engine as used on the MGF, MG TF and MG ZR160.
In that form it puts out 142 BHP, but with a 52 mm throttle body and uprated air filter it will be approx 165 BHP. Maening a power to weight of approx 300 per Tonne. ie very fast.
I have plumbed for nearly the same doner car but a little newer, a Rover 25 GTI.
Be careful though to ascertain the condition of the engine, older variants usually blow the head gasket. Not a major problem if it was caught early enough. Though at worse it can mean a new head.
You would be looking to renew the HG anyway along with the cam belt(s). Which is not a major undertaking and adds to your knowledge of cars and engines.
If you do go that route let me know as I have the Genuine Rover build and reapir manuals (upto year 2001) on CD-rom and would be happy to send you a copy of it.
I pick up my kit soon from Marlin soon (have been and still delayed with the garage build) and this is my first foray into kit car building.
Go on do it you will have loads of fun and end up with a fantastic car that is very quick and the envy of your friends.
In fact because of the insurance situation with your age, buy the Rover Vi, and then you can buy seperately and very cheaply a 1.4 K series engine (104 BHP) and install that. This would be still quicker than 99% of the cars on the highway PTW 190 per tonne. Just check out the weight of most cars!
You can run up a years no claims bonus with the 1.4 installation, learn the handling of the car then put in the VVC engine which you will have then rebuilt.
Sound like a good plan even if I say so myself.