Originally, the plan was to port the head, fit throttle bodies, re-profile the cams and use ARP con rod bolts to allow the engine to rev higher on the standard con rods. This setup is used quite successfully in many engines, notably the C20XE. A crucial part of that setup is stronger con rod bolts. The standard rods would have been good for 7500RPM, if not a little more but not without a bolt upgrade. Unfortunately, neither ARP, Pankel, nor anyone else who make suitable quality fasteners had anything suitable and the price to have them made was approaching the cost of having a custom set of con rods made.
This was the turning point in the project. In the space of a couple of emails, it went from fast road spec to just shy of balls-out race spec.
The final issue with the standard rods was the lack of decent quality con rod bearings, required for high RPMs. The workaround for this was to polish the journals of the crankshaft slightly and have new con rods made to take a bearing from a different engine - one which had race quality ACL bearings available. These new forged EN24 steel rods were custom made by Robson Engineering (Farndon), are lighter and will easily cope with the now planned 9000RPM rev limit.