You can order nice tubular Cro-Mo pushrods from Isky. Either in the length to work with stock lifters or slightly longer ones to work with the slightly shorter SBC lifters. You do need to use a new set of lifters with the new cam, anyhow, might as well just go to the SBC style.

Part numbers and prices from iskycams.com:
VL-013 - pushrods for stock lifters ($60 - set of 8)
VL-123 - pushrods for SBC lifters ($60 - set of 8)
202-H - Solid SBC lifters ($53 - set of 8)

When I was building up my PV's motor last time, I tried to use my old set of Isky/IPD tubular pushrods. And found that even with the adjustments backed off all the way, the valves were slightly open still. Apparently a whole bunch of things had all added up to significantly reduce the height from the cam to the rockers.
1) I had the block decked during rebuild to zero the piston height
2) I have an R-Sport head that has been shaved *way* down
3) I have a KgTrimning rocker shaft support bridge that lowers the shaft slightly for better geometry with big lift cams
4) And last but not least, roller rockers on shaft, made of aluminum, and slightly different shape.

Isky will make custom pushrods in any length with any end styles you want, but there is an upcharge for custom work. But I was able to go through their catalog and find a standard pushrod that was both the correct length for my needs and had the proper ends on it, so I just ordered them instead. So my car now has MG-TD pushrods in it.

--
'63 PV544 rat rod, '93 Classic #1141 245 +t