Engine combo advice

In response to question #1
Please dont hate me, but,I have to ask, is that cam already in there?
I think that cam has too little .050 for its advertised .006.That is to say, its rate of lift could be a lot better.It will not trap cylinder pressure as well as some of Comps other offerings.Its rate of lift is gentle on the parts, but,the Dcr will be a bit on the low side.
Your Scr will come in around 9.4, and the Dcr will come in about 7.8@sealevel.
Now couple that with the 3310, and the 2500TC. First gear will be ok with the 3.55s and the 2.54s, but second will lay down a bit, and in direct once the engine has to really work,it could be a lot better.
So if the cam is not yet purchased I would strongly recommend a cam with a shorter period advertised and a longer period .050.
For instance, they (Comp) have a 262Extreme Energy that offers the same 218* @050,but just 262*advertised.This cam wil increase your Dcr to 7.95, and make a little more power, and noticeably more torque.Not a big difference, to be sure, but it also offers 6* extra in the exhaust, and will/should, make better Mpgs.
There are also faster rate-of-lift cams from other manufacturers out there, that could bring the Dcr up closer to 8.2, with a torque and power gain as well.
The Dcr increments are somewhat deceiving A 0.15 to 0.2 change is a lot. I can be the equivalent of one cam size.
So again, If the cam is not yet purchased, at least consider bumping the Dcr up with a drop in advertised duration, but not giving up any .050 duration. There is no downside to it.
But if you already own that 268, and its already installed,well, it will still be a fun engine.