Look for this Block # ______ in a truck with a forged Crank 2 or 4 Bolt considering a cast Crank will get you to 6400rom and 550 Hp - (let me find the Casting #) if not with the Forged OEM 454 Crank, buy a an Eagle Forged Crank searching for 7000rpm and over 600Hp, 2 or 4 Bolt Block s not essential. Use ARP Main Studs in a 2 Bolt & consider a Fabricated Windage Tray with a 7 Quart Side Kick with Traps after 6200rpm.
Costs Add UP - Particularly the Valve Train in a MK IV.
NOTE: I kinda like the Cast 454 Crank; It`s Lighter and Revs like Crazy to 6400rpm easy 525Hp compared to Heavier Forged Unit which is capable of 7000+rpm over 600HP but the Valve Train Costs more then the Mill, as your looking at Ultra Lite Severe Duty Valves with either a Jomar Girdle or an Expensive Shaft Roller Rocker System.
Between 9.5 to a 10.7:1 Static Compression on Pump of course. About the only Cheap Solution - My Suggestion - is the Hydraulic FT 6800rpm Cam with ARP Rocker Studs and descent Roller Rockers is the CCA-XM278H-12 with a 9.5 to 10:2 Static Compression with CCA-924 or 925 Springs short shifting at 5800 hoping to it it all in by 6200rpm, Holley 750Dp/Elelbrock RPM Intake - After 10:1 Static you should consider an Expensive Forged Crank, Forged Pistons and either a SFT or SR 7000rpm Setup = In my opinion, NOT worth the Expense for another 100Hp & 100 ft/lbs or torque , considering the Drivability with a MKIV - Unless your 1/4 Mile Racing and EXPECT Everything to Break - Just ask Fred - LOL.
Not saying you can't get away with a 600Hp+ 7000rpm SFT or SR MKIV on the Street with Pump Gas; providing you treat her Respectively.
I do the Forged 7000rpm Conception based with a a with a 460ci 73 LS4 MKIV Lunati SR/3:31/M21 70Z - Haven't blown her up after 6 Years and Running Strong
Is the Money over the CCA-XM278H-12 Worth it (I Love that Cam) - NOT - That Cam Provided me with everything simply because, I can't Plant my Shoes with P295 X15" Comp T/A Radials - Want a Street or Road Race - God Bless You.