XR274HR-10 in 318

Yes on the 9:1 BUT realize that the factory published compression numbers were exaggerated. if you work the actual dimensional data, it works out that way every time. And it was not just on Mopar engines!

Too big of a cam will lower the low RPM torque. That is why the question on how you plan to use the engine. If you are drag racing all the time, then you don't care. The high RPM TC stall is to allow the engine to rev up on launch past the poor-torque low RPM range when a big cam is put in.

If you are street cruising, then low RPM torque is a big contributor to 'driveability' and good throttle response. So you change your approach there and keep the cam limited in duration and use a different cam profile to help the mid-high RPM HP with less effect on low RPM torque. Some guys like revving the car all the time, but some don't want that.

If you don't want to hurt the performance in any way, then I suppose that means you don't want to lose an low RPM torque, and a different a cam is a much better choice. But it would help if you stated you use and goals for the car, rather than us guessing.