help me come up wiht a value.

[Lightspeed]

71 chevy, short stepside. 76k miles on body. was originally six cylinder with 3 speed on column, now has 70 LT1(un-original heads intake and carb) and a muncie four speed. engine was rebuilt about 3 years ago and has hardly any miles since. truck is pretty solid except for some pitted rust(no holes) around drip rails. also the floorboards have about a 2 inch by 4 inch rust hole on both sides. what do you guys think? im not really planning on seling it, im just curious as to whether i got ripped off in buying it.