I've been toying around trying to come up with a hydraulic roller version of the ZZ520 build.  Here's what I have so far..it's nowhere near as cheap as '03 prices.  A similar build made 506 HP with slightly different valve geometry and higher compression.  Scoggins-Dickey offers a blueprinted ZZ4 with zero decking that would give 10.2:1 compression, probably pushing this engine to around 510HP max.

I'm using GM lifters to cut the lifter price down.  This means using a reduced lobe base circle with a higher lifter ratio in order to keep the lifter in the lifter retainer.  The camshaft would need to be a custom grind with the same lift and duration as the XR300HR, but with the new valvetrain geometry in mind.

I downgraded to Magnum pushrods from Hi-Techs to save some cash.  However, for more lift and HP, I could upgrade to Hi-Tech pushrods and 1.8 ratio rockers, still retaining the OEM style lifter.  At that point, it would be wise to upgrade to a Comp Cams lifter, but still skip out on the link-bar combination, as that nearly doubles the price of the lifters.

On a final note, if I wanted to do an all-out upgrade, I'd drop another grand on a Dart 03113722 short block and add 250HP of spray.

Description..............PN.............Price.......Supplier
Carb.....................132-1563020VF..$.460.....eBay: Rich Desbiens
Plugs....................ACF-41-629.....$..16.....Summit
Heads....................AFR-1040.......$1441.....Summit
Cam Bolts................ARP-134-1001...$...5.....Summit
Cam......................xxxxxxxxxxxx...$.260.....Custom Comp Cams
Cam Install Kit..........CCA-08-1001....$..89.....eBay: Atlantic Speed
Rockers..................CCA-1302-16....$.275.....eBay: Atlantic Speed
Fuel Pump Pushrod........CCA-4607.......$..13.....Summit
Pushrods.................CCA-7372-16....$..93.....Summit
Intake Manifold..........EDL-7501.......$.219.....Summit
Head Gasket..............FPP-1003.......$..59.....eBay: cj11l
Intake Gasket............FPP-1205.......$...6.....eBay: cj11l
Exhaust Gasket...........FPP-1404.......$..17.....Summit
Spark Plug Wires.........FRM-96292......$..32.....Summit
Breathers................KNN-62-1490....$..38.....Summit
Oil Filter...............KNN-HP-2002....$..11.....Summit
Oil Pump, Driveshaft.....MEL-10552......$..63.....Summit
Pickup...................MEL-12559......$..16.....Summit
Lifter Valley Screens....MIL-23150......$..20.....Summit
Oil Pan..................MIL-30702......$.100.....Summit
Filter Adapter...........MRG-1270.......$..11.....Summit
Oil Pan Gasket...........MRG-6561.......$..30.....Summit
Head Bolt Washers........MRG-87..... ...$..10.....Summit
Timing Chaing............NAL-12371043...$..52.....Summit
Head Bolts...............NAL-12495499...$..26.....Summit
Lifters..................NAL-12499225...$.122.....Summit
Damper Bolt..............NAL-12557840...$...5.....Summit
Short Block..............NAL-12561723...$2300.....Summit
Damper...................NAL-88960604...$..85.....Summit
Fuel Pump................SUM-250020-1...$..55.....Summit
Distributor Clamp........SUM-400500.....$...5.....Summit
Engine Bolts.............SUM-56490Z.....$..15.....Summit
Distributor..............SUM-850001R....$..90.....Summit
Carb Spacer..............SUM-G1408......$..17.....Summit
Valve Cover Gaskets......SUM-G2301......$..12.....Summit
Front Cover and Gaskets..SUM-G3200-K....$...5.....Summit
Valve Covers.............SUM-G3302......$..54.....Summit
Dyno Break-in and Testing...............$.475
Freight for Summit......................$..99
Shipping for Atlantic Speed.............$..11
Shipping for Comp Cams..................$..20
Shipping for Ottawa Engine Perf.........$...8
Shipping for Premier Mold...............$...6
Shipping for Rich Desbiens..............$..22
Shipping for Summit.....................$..12
Total...................................$6786  

wow, this forum is dead.  RIP CarCraft.