Cosmo,
As you most likely already know, the 58-62 261s came from the factory with full-pressure oil filter system. The original cartridges are still available, or you could convert to a remote spin-on system.
The 261 that I am still using is a 1960 engine that I rebuilt in Charlottesville in 1972. I ran it for years with stock intake/exhaust/carb/electronics. It was reliable and was noticeably more powerful than the original 235.
If you want the simplest, least expensive upgrades, just slap on your 235's intake/exhaust parts and go with that and your existing drive train. If/when your carbs ever start acting up, convert to Langdon's Carter-Webers (and his C-W linkage).
The 261 cam is already a modified lift cam (the same used in mid-54to55 Corvette 235s). You can get this idle down to below 450 rpm - a higher-lift cam would most likely roughen your idle.
You could use your 848 head (drilled to match the 261's extra coolant passages), or you could wait to do this when/if the engine needs a rebuild.
Tim
