Hey good choice for a LBC! I'm still running 145 sr 13 Michelins on my car, and there is not much room left as it is... A 165 70 13 would fit. ( my tires are very old stock, and quite hard and slippery, but complete the stock look of the car very well..).
You probably will find that you don't need a lot more power out of the car as it is stock. Use a set of sprint cams, balance the motor, get a lighter steel flywheel if you can, match the int and ext ports, put a header on it with a larger bore exhaust ( not an easy fit, and watch those speed bumps..)cc the head and degree the cams ( the cams and gears can be wildly out of spec from the ideal..).
Lastly you might consider using a set of Del'Orto carbs. They start and run better, and have a smoother progression from part to full throttle. There is no power difference, but a big driveability and part throttle performance difference. I have run them on other motors and currently am running them on my Cortina, and loving it.
Take an Elan out for a drive if you can find one. You need to see the kind of power band that you are trying to play with. These motors have a very flat torque curve, and never really " come on cam " like most other motors. They pull steady and strong right up to redline and beyond ( hence the rev limiter rotor supplied stock in every Elan )
Building the motor for higher performance won't change these characteristics much, these are definately not motorcycle engines. If you want more power the best way is more displacement. You can build a stock block 1600 cheater motor, or build a tall block 1650 to 1700 torque monster. I chose the torque monster, and it works very well indeed. I would guess my power at about 135 hp, but I can drift the car around long sweeping corners quite easily in second gear ( haven't tried it in third, that's way too fast for me.)
I would advise against drastic gearing changes, like 411's or limited slips. On the street.
Well anyway you won't find that you have a problem with spinning just one wheel, in fact you will have trouble keeping the car pointed in the right direction as it is.
Enough said.. I'm not an expert on these cars, having only restored one and helped on another. I don't race mine ( or anything for that matter ) so maybe you should seek counsel from some people who actually have gone whole hog on their cars. I will say that the returns you get for the money that it will cost you to bump your HP up even just 20% should make you stop and think hard about it. ( just a used steel crank can cost you $1500.00 ) Been there, not doing that again thanks /ubbthreads/images/graemlins/nonono.gif