Here we go again!
I am not aware of a V8 conversion how to article, but all you really need to do is look at a Sunbeam Tiger. George Boskoff figured out how to do it 40+ years ago and nothing has changed.
I can give you a partial list of what is required.
– Remove the Alpine firewall and fabricate a replacement.
– Remove the Alpine transmission tunnel and fabricate a replacement.
– Remove the Alpine steering system and fabricate a replacement.
– Relocate the Alpine brake master cylinder and fabricate new pedal linkage.
– Fabricate new engine and transmission mounts.
– Modify the Alpine frame with pass-throughs and notches for the exhaust system.
– Relocate the battery and remove the Alpine battery box.
The V8 conversion can be and has been done more than a few times. When you get through, you will have a Tiger clone, better known as an "Alger". You will get absolutely no respect from the Tiger crowd and the car will probably never have enough resale value to cover the conversion cost. If you are interested in the resale value, you would probably be better off to simply buy a Tiger.
Not only is there "how to" information about a V6 conversion, there is even a well designed, beautifully fabricated and very well supported conversion kit using the Ford 2.8 V6. The moderator for this Forum (JimE) will probably be along shortly and he can let you know how to get in touch with V6 Jose.