New to Z's need some advice

[theAntihero]

New to to the forum and to Z's but i wanted to get some advice on a project im thinking of doing.

 

Ive always liked 240z's but ive always put off getting one, i think its time now, but im not terribly impressed with the stock engine and power. Add to the fact that my area has a good amount of cheaper z's that have engines on the downhill side and youve got my project : a 240z with a SBC.

 

I want something that has enough power to be fun(and fast) but gets decent mileage, a lot of people claim to get in the low 20's with an overdrive tranny and a 300-400hp 350/383, how realistic is this? If this is at all true this sounds just perfect for me. Now we get to the super nOOb stupid questions:

 

If my goal is in the 300-400hp range which would serve me better, a 350 or 383? Im not looking to turbo or supercharge here just a simple naturally aspirated, carbed engine.

 

What manual tranny should i be thinking about that can handle 400hp and can work without lots' o fabbing that can still get me in the 20's mpg?

 

Ive read that the stock rear end can easily handle 400hp, is this true?

 

The end goal of this car is to be a sleeper fun,fast car. I dont care if i get loads of street cred for it, in fact ill probably just paint it flat black and go with it. I might even leave the stock exhaust(or something similiar and more restrictive) and have exhaust dumps hooked to something far less restrictive and very scary sounding, maybe have them a bit hidden so a quick glance doesnt notice it. It might be fun to see the looks on some of the more pretentious sports car guys around here when the realize that my Z is far more powerful than their insert-car-model-here.

 

Also i have some mechanical ability, ive swapped engines and worked on a lot of older vehicles and my father is a pretty fair mechanic and is willing to help, so id like to stick to the easier bolt on side of things on this project, maybe later we'll go to the Z with a Saturn rocket swap but for now its probably out of my reach.

 

Thanks