Need help with restoration...

[bazkook]

I'm restoring a 1970 C10 step side and I need some advice. The truck has a I-6 with a 3 speed on the column but I plan to put a V8 in the truck,a 700-R4 transmission,a 12 bolt Eaton posi rear end(with the original 3.73 gears),and several other things.
I want to stick to the following guidelines when working on the truck:
-Street legal,of course
-Maintain drivability:plan to drive on weekends and special occasions(such as when some ricers around town need to be taught a lesson or two),at least 10 mpg,not to rough to ride
-Able to run at least high 11s in the 1/4 mile(hopefully better than that)
-Lighten the truck but keep the AC and other comforts,weight savings in other areas
-Keep the cost of the restoration below $20K

With the above stipulations in mind I ask these questions:
1.What would be a good engine for the application? I want to use a crate engine but I plan on using nitrous and that would void the warranty on most crate engines. I would like to stick to small blocks but I would be willing to use a "smaller" big block if it came down to it. I was considering the 490 horse 383 made by MAS Performance but I still exploring other options.

2.What would be the best way to lighten the truck up? I thought about replacing the steel front end with a fiberglass one and the bed or rear fenders with fiberglass also but I am concerned about the fiberglass shattering if I were to wreck the truck. What material would be the strongest and most durable but would give the most weight savings and bang for the buck?

Any advice would be appreciated. I believe that's all the questions I have for now but if I think of any more I'll post them. Thanks!