First off, Eric, I would prepare the car to the specs of the most conservative club you are likely to run with. Just gives you the most options. Shanabrook and others seem to do just fine with no flares. Now all they need are full-tread radials or bias-ply tires to fit in!
Flares are a big, big hot button with Jackl Woerhle, the Tech Cahir of SVRA. If you have VSCDA flares like Rod Beer, Steve Fog or the Stark-mobile, you may be in class 8 RS (IMSA mid-'80's, anything goes) or, heaven forbid, Group 10 with SVRA.
If you run somewhat more conservative "riveted" flares or "eyebrows" over the rear wheels, you may run in class 8 BS.
If you run a straight-fendered car, you won't have any problem, and if you run a 1750 with no flares, you'll FOR SURE be in Group 3 (like Sam Cummings car)
IMHO, VSCDA spec is so subjective that more and more sanctioning bodies are discriminating against that spec.
If you prepare to SVRA spec, you can run advantageously in SVRA, VRG AND VSCDA.
bsedan.com and twofivechallenge are West Coast-only deals... All vintage clubs are really local...
Just depends on who you want to run with...