Long strokes not revving is sorta one of those internet wives' tales. A 4.250" stroke will be zippy with the right combination and the compression ratio has a lot to do with that.
This cam would peak considerably higher, which would let you take advantage of the cylinder heads and intake. The BBM TW intake is very large and you're probably at a detriment in throttle response and power in the low/mid ranges. Now granted, you'll still be lighter on the bottom end because of the heads/intake, but the cam would let you gain some in the top end and the 3.89 gears would help you get that big car moving on the bottom.
You'd be in for a considerable expense though.....the cam isn't expensive, but you'd need lifters, a distributor gear, pushrods, and possibly a valve spring change.