Small block or Big Block

[KahunaEdd]

I have a 69 GMC 3/4 ton long bed. It is currently bone stock. I did a full restoration 5 years ago utilizing the factory build sheet. It came with a small block V8 and 4sp manual trans. It is time to put a new motor in the beast. The old motor still runs strong but leaks oil from every possible place an engine can leak oil. 1qt per month. Even with a pan underneath, I was kicked out of the garage and now being evicted from the driveway by my wife. With 186K mi I got my $ worth from the original motor. I have the opportunity to either replace the old motor with a 330hp small block or a 450hp big block. I am leaning toward the big block because I think it will make the truck more desirable. The old motor still gets the obligatory 12mi per gallon. I am not sure what the new motors will yield MPG but I only drive about 100 mi per week. Any sage advice? This truck is my daily driver, I go everywhere in it.