My 1987 Formula brochure shows a weight of 3750. I'm not positive, but I bet this weight is with a 5.7 package. I would add another 400 pounds for the big block and bravo one.
I have an 1989 223ls and it is listed as a dry weight of 3700Lbs with a 350. Mine is a 454 (with a Bravo, not an Alpha) and I think it is 4050 dry weight if I remember correctly.