Hi Keith,
I have thought about building a V8 early Alpine myself. As I see it there are two ways to do this the hard way is to try and make it as near a Tiger as posible the other easier way is to make a fun car with a V8 and avoid buying all or most of the Tiger stuff to put on an Alpine. There is a fellow on here who has done this and is doing it again and he would be a big help for you. [Chuck chime in anytime] Chuck has converted an alpine cross member to a rack using MII spindles do not recall what rack he used. Think a tunnel could be made up with out a huge deal of trouble. Might be nice to get a set of Tiger frame mounts for the engine and there is someone selling a repop trans mount. This would all get you there will be a job of work none the less. Oh and I would go with a 8 inch rear end instead of the 8.8 lots of fellows are using the 8 inch in the V6 conversions all are avoiding the 8.8. Would sugest checking into the cost and problems with narrowing the 8.8 before spending any money on one.
Then there is the V6 conversion which is much simpler.