TTi step vs. 340 manifolds

Is the motor still stock low compression?
As far as I know. I have a set of small valve 915’s that I want to have worked over to go on it (milling, 2.02 valve, racing valve job, port work). Currently has a Z and an O head on it.
Currently has a stock 340 iron intake with the divider cut down and knife edged. Planning on putting the LD340 on it when the 915’s go on.
Right now it is a single leg 8.25 with 2.71 ratio. I will put a Sure Grip in it with 3.21 or 3.55’s. I do plan on driving it on the Interstate for a couple hours at a time so leaning toward 3.21.
The cam is a single pattern 224 @ .050.