I finally got to mock up my cylinder head and valve train! None of the rocker arm covers that I have will clear the stud girdle and I would have to file off the outside extreme corners of the two end pushrod guides. The existing covers also crowd the two end rocker arm trunions and I'm not fond of that either. If I were using aluminum rockers, I'd have to shave the corner of the to end rockers to clear the cover.
I'm going to take one of my cast aluminum Mercruiser covers and cut the flange off of it. I've got a pair of SBC extra tall, cast aluminum covers, so I'll remove the flange from one of them, TiG it onto the 4 cylinder flange upside down. This will create an adapter to use the other SBC cover and eliminate any unwanted modification to the valve train. Using the small block cover will furnish extra space for the entire assembly operate and save me having to fabricate an entire rocker arm cover!!
