A basic spec1967 Mk1 would have most likely been an 850 (might be on the heritage certificate?), but for practical road use a 998 would be better.
If you have to rebuild the suspension there is really no point in trying to put hydro back in unless you have all of the parts already in excellent condition. The dry suspension is easier to fit, more reliable, but a slightly harsher ride. I don't think there will be much difference in car value between wet and dry, unless you are going for a totally original concours spec.
If you are buying subframes make sure you get the right type. Should be 4 bolts fixing to the front crossmember (2 each side, used up to 1976), and if you are fitting a manual gearbox get a suitable manual front subframe. You should be able to get this second hand without too much trouble.