Compu cams XE268H question

I would stay with the XE268 and yes, change the springs to the 901-16s. They drop in place with no other parts needed.
The MP cams are hit or miss in terms of quality, and in direct comparison to the XE line, the lobe designs are archaic. You're building an old engine so maybe that works for you. If that's the case you will also need to change the springs with the MP cams, and you really, really have to degree them. You'll want to run either 284 or 509 advanced so buy the timing set with multiple keyways.