I have a stock SIV ST OD that will be back on the road with a very nice 1725 rebuild maybe soon. I bought it early 1980, a couple of my kids drove it! I too enjoyed it. With the engine showing some wear and the oil pressure dropping, it was stored in mid '80's.
Afterwards I bought a SV (currently my Blue Boy V6), with all the original running gear. My elder son ran it hard. Parked it in for storage and joined the Army.
I got hooked on the V6 idea from Jose. Bought one of his kits for my "other" SIV BW35 GT, a piece of junk that was given to me. I started the conversion based upon what I could find on the Forum and from lots of communication with guys that had Been-there-done-that
None had thoroughly experienced what I was being confronted with or going thru entirely.
There was no tranny bracket on the market for the conversion of the BW35 Automatic Alpines, atleast not known at the time.
I had to develop my own. After many hours of trial and error, I had one that worked very well. Later scrapping that design I did another which I currently offer either individually or as part of my components for the conversion.
Many hours and lots of money was spent on the next few items I currently offer. Engine mounts for one are as well designed as if by one of the Automotive Companies.
Perhaps the hardest and most difficult was a better design for the headers that would complement the 2.8 V6 in an Alpine. I was convinced that they needed to run straight back along side the engine and transmission similar to most other "street cars"..... I liked the design that was made for the Tiger!
While it is a tight fit, no argument there, it is a near perfect piece of workmanship for converting an Alpine from a 4 cylinder with under 100HP to a more modern vehicle that can be driven any where (Interstate Highways).
A little effort can be exerted to make the V6 an even more comfortable & enjoyable vehicle too! I added an A/C system to my Blue Boy while it was stilled powered by the 1725 engine, it functioned well, however the V6 much better.
With an Electric Power Steering for the Sunbeam Alpine the driving experience is easy on the hands. The telescoping system if so equipped can be retained or added should your Alpine not already equipped.
Most recommendations have been to convert the stock 2 bbl intake on the V6 to a 4 bbl. I followed along that line. I really like the 390 Holley and the OFY 4BBL setup. However, much has been discussed on other options for fueling the V6. Study what is out there and make your own decision.
Very little modification to the structure of the Alpine is required. The Alpine engine mounts are welded to the crossmember, they need to be removed. Replace them with what works best for you. I like mine because they are strong, easily mounted and provide a "fixed" position so the engine and fan/radiator have sufficient clearance.
The only other necessary for fitting the transmission of choice, the late model Mustang T5/Auto C3/4/A4LD being a few choices currently utilized. There is less modification to the transmission tunnel on the 4 speed Alpine if utilizing an internal hyd release bearing and potentially less with the A4LD tranny. The BW35 Alpines have a much wider tunnel and are best candidates for the V6 Conversion.
Lots of opinions out there! I have always suggested you READ! READ! & Read some more before jumping