try to get a complete pullout or the little parts not only add up... they take a lot of time to source.
An LS2 motor with upgraded cam/valvesprings, long tube headers, and a tune should make an easy 440rwhp+.  Ported heads add 30-40rwhp.  FAST intake another 15-20rwhp.  
Cubic inches make power.  It also costs a hell of a lot more 
 
 
A built 427ci LS7 with WCCH ported heads/upgraded cam/ported intake and long tubes should make 550-575rwhp+ on pump gas.  It would also have an additional 100rwtq over the LS2 simply because of cubes.  Figure $12-14K to do one complete.
As they say... you gotta pay to play 
 
		
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				Project: 1969 Chevelle, alum 5.3, GTS76 turbo, Chiseled Perf A/W intercooler, Holley Dominator EFI, Davis TC, JRi coilovers, 14" brakes, T56 Magnum. CTS-V Recaro seats!  
Coffey Fabrication Nashville, TN doing the fabwork! 800rwhp+/25mpg+/9's@150mph goal 
 https://lateral-g.net/forums/showthread.php4?t=52976
1993 Mazda FD RX-7
 
https://lateral-g.net/forums/showthread.php4?t=52976
1993 Mazda FD RX-7, built LS7, T56 Magnum, Holley HP, Davis Tech TC, 8.8" 3.73 Cobra IRS diff, DSS axles, Ohlins coilovers, big brakes.
CCW 18x11 front 315/30/18's and 18x12.5 rear on 335/30/18 RA1's, 
2850lbs
10.31@137mph 165mph Shift-Sector 1/2 mile speed
441ci AllPro headed motor and 200lb weigh reduction in the works....