I have a 1954 Chevrolet 5 window truck that my great grandfather bought new in 54'. He gave it to my grand father (Robert Nance aka Mr. Plymouth) who rebuilt it and replaced everything with mopar guts. He did this mainly because he loved Mopar, owned a dealership, and was one of the original factory sponsored drag racers.
Anyway, I am going to restore the truck back to its glory and I am going to keep the mopar drivetrain because he would have wanted it that way and be cause I love Mopar.
What I need help with is I want suggestions on how to build this 360 engine to get maximum hp without sacrificing dependability on pump gas. I want this truck to beat the ground. The block is stock with about 50k og miles.
Please help.  

I would like to get 500 hp. Is it possible?  

Best way would be to build a stroker motor by making your 360 a 408. After that you can hand pick the rest.   Edelbrock aluminum heads ported, polished of course.
I would use a solid or a roller cam in the 560 lift range, with 248 duration at .050. Also a good set of roller rockers, either 1.5 or 1.6.
At least a 750/800 D.P. holley, depending on the weight of the truck of course. If this thing weighs 3500+ lbs. stay with the 750.
Intake, no brainer Edelbrock air-gap.
Hooker Competition Plus ceramic 1 7/8th headers.
Now that you have 500 + horse power your going to need a very good 727 trans, high stall 9 1/2" converter, rear end in the 4.10 range with a nasty set of tires that will hook this monster up.  

Now where would you recommend getting my parts? What should I get For ignition system?  

MSD 6AL is the best street strip ign. available and its easy to install.
As far as ordering parts, look at Mancini racing for the bulk of your order, their prices are great and the service can't be beat.
For the rest of the engine parts I would go to Summit or Jegs.
For the trans. parts Dynamic Converters can't be beat.
Good Luck.