You're joking right?
1 horse per cube is fairly easy to do with a modern rebuild (notice, I did not say "cheap"), even without aftermarket heads. According to 440 source their heads will support over 550 hp out of the box, so that shouldn't be a problem. Get your compression up to 10:1, with aluminum heads you might be able to run it up a little higher and still run pump gas. Then get a strong cam, newer aftermarket intake, and headers. The cam selection will be the big deciding factor, for 450 hp you really shouldn't even need that radical of a cam. 500 hp is
very do able with a stock stroke 440.
I'm not a big block guy, so I'm sure others will have more specifics. How do I know that the numbers you want can be that easily achieved? These are the specs of 2 different
360 builds, both of which put out over 450 hp and should run on pump gas. Complete page is here, it lists 9 360 builds with dyno results, just for thought
http://www.mopar1.us/dyno.html .
Package eight:
360 rebuilt with 9.5 to 1 cast pistons, original crank, rods and windage tray. 202 heads with competition valve job and ported to flow 260 cfm. Edelbrock RPM intake, Holley 750 rejetted, Large tube headers and Mopar Performance P4120231 cam with .484" lift, 284 duration, 108 lsa, installed at 106 intake centerline.
460 h.p. @6000 rpm
486 lbs. of torque @ 4,250 rpm
Package nine:
360 rebuilt with 10:1 compression flat top cast pistons, original crank turned .010"/.010", rebuilt factory rods. Factory windage tray installed. 2.02" heads with competition valve job and ported to flow 260 cfm. Edelbrock RPM intake, port/gasket matched. Holley H.P. 750 (.076" front, .080" rear jets). Large 1 3/4" primary tube headers. Comp Cams 305AH-8 camshaft with .525"/.540" lift and 305/312 degree advertised duration, 253/260 degrees @ .050", 110 lsa, installed at 108 intake centerline. This motor is a brute for a street car and would only be considered a weekend blaster.
495 h.p. @ 6,000 rpm
500 lbs. of torque @ 4,500 rpm
You'll notice "package 9" is a 360 that meets all of your criteria. Not very street friendly because of the cam, but, its still a naturally aspirated, non-stroker engine that's short 80 cubic inches and still meets your goals.