[Frankenstang65]

geno5.0, first nice kill...gotta love putting those WS6's in their place.
Second, nice car. It pays to buy a car that someone else (as long as they knew what they were doing of course) has done modifications to. Based on what has been done to it, and the way it seems to be performing, I'd say you got a pretty good deal.
Third, I've got a friend with almost the exact same set-up in his 5.0. The only difference is that he has all MSD ignition, 3.73s and a stall (don't remember which one). He was able to rip off a 13.4@ 104.5.
I would agree with sedanman and estimate you'd run somewhere in the 13.7-13.8 range at around 104.
I would also agree with sedanman's idea about tracking down the previous owner. It'll finally give you an idea of what you got, and will take the guesswork out of planning future mods that may or may not be compatible with mods that you may or may not have. See what I mean.
Anyways, sweet car man...I hope that helps.