Easyest, Cheapest way up to 500 crank hp?

cheapest?

HAha...what kind of durability? 5 passes or less? That answer is stock engine, $1000 worth of nitrous goodies, and up the nitrous and retard the timing till the headgaskets let go.

Most beneficial/durable 500 chp = Stroker NA SB

Most powerful for the least amount of money? (turbo) Forced Induction + Nitrous.

I hate these kind of questions.
Tell you how I AM going to get 480+ hp at the rear wheels.......

Stock 1989 360 Roller Cam longblock, with addition of my 3-18-1973 360s' windage tray and oilpan
Stock Cam
Stock Springs
Stock Pistons
New Double Roller Timing Chain
New Mopar P5007709 Timing Chain Tensioner

Here is a Excerpt about it:
TIMING CHAIN TENSIONER
This Timing Chain Tensioner stabilizes cam timing by reducing timing chain slack. It can be used in place of thrust plate P5249637.

P5007709 Timing Chain Tensioner (Small Block and 3.9L, 5.2L, 5.9L Truck Magnum/Jeep� Engines) $ 32.95

New Gasket Set
New Brass Freeze Plugs

Stock 1989 ~ 308' casting 360 heads, fresh valve job, new valve seals, intake ports Gasket Matched, smog ports welded, new valve seals.

Edelbrock RPM Air Gap - Gasket Matched

Holley 750 Double Pumper, modified for blow through, 3.5" inlet carb bonnet

1974 360 Duster~ Exhaust Manifolds, Dual 2.5" custom cross pipes to 3.5" Turbo pipe, to 3.5" SINGLE exhaust

Precision Turbo Engineering PT6776 turbocharger , .96 A/R, non ball bearing, non water cooled....good for 750hp.

Stock non MP vacuum advance distributor that will be recurved for proper boost manors.

Non-Intercooled...but am considering water injection...7psi daily or (low boost) 14 psi (hi boost)...which theoretically would be 420 rwhp, and 600rwhp respectively....all hypothetical of course, till I do it and show everybody.

Thats pretty much my engine, carb to pan.