my 90 LX was nowhere near 2900lbs…it was within 150 lbs (around 3400lbs) of my 70 Stage I 4 speed car (490hp/650ft lbs of boat anchor torque). The 90 LX was good for around 330rwhp and ran great…but not to level of my boat anchors when they are in a similar state of tune. These Buicks are one of the lighter musclecars around and a very light A body in general (the 455 engine is within 20-30lbs of a small block Chevy)
As far as I’m concerned, I welcome guys to keep thinking like the earlier poster…those are the guys that can’t believe they just got spanked by a boat anchor
Back to the original thread question and forgive me if somebody already suggested it…the newer generation 302/5.0L offerings from Ford (87-91) are probably the some of the best running engines in terms of overall performance Ford has available. they respond well to modifications, they easily surpass a 1hp per cubic inch output and will run 25mpg+ due to the effiency of the fuel injection. My 90 was nearly 28mpg once the engine and exhaust was freed up…something very few 350hp+ engines can lay claim to (Chevrolet Corvettes are a great example of fuel injection providing both performance and mileage).
If you can afford it, I would look at newer technology and really build a neat retro rod. Another point to consider if you do so…the 87-88 engines form Ford were speed density systems in stead of mass air systems. Both have benefits, but in the hot rod circles back then the speed density engines were the hot ticket for making max hp.