Having most of my time in original AC's from the 63/260cid & 64/289cid slabsides to the 66/427 (HM) sideoiler (CSX#3116) & a 68/428cid street. I took my time finding a worthy replacement ride. I rode/drove various replica models, Shelby, SPF, FFR, ERA & Unique. In the end, I went with a ERA. It was just the most true and authentic to my memories of what a AC roadster was and should be; an exacting replica.
90% of ERA's are factory built rollers/turn keys. So the build quality is dead on!
Yes the ERA S/C is 2,600 lbs to the original CSX's 2,200 lbs. That is because of glass & a much stronger frame. The ERA for me at least was the best choice. That being said my 1st choice for Alum. would be KMC, then Shelby. My 1st choice for glass is ERA, then Unique & SPF. However if you want to go wild!
Buy a FFR MKIV & drop in a (460 cid) for about 11K w/off the shelf parts & pushing 750 hp!
For the ultimate low budget Rat Killer! That should run less than 50K, saying you do most of the work. Or look used here, or cobra country