That is not exactly correct. Slants are notorious for have stock compression ratio's in the high 7s to low eights. So raising compression is always a good idea. Even with a 1bbl carb increasing compression will increase low end torque. Be sure to measure piston recession and cc the combustion chambers, use an online compression ratio calculator to get to your desired compression. Personally I think a target of 9.5 may get you into the need for mid grade gas, especially if you stay on course with a small cam. I would go with 8.5 as a target. Here is a link to one of the many online compression ratio calculators.
RSR Static Compression Ratio Calculator
IIRC shaving a slant six head .0699 will remove 1 cc from each of the combustion chambers.
A slightly more aggressive cam will also help, if you choose to retain the stock cam, have the fuel pump lob inspected for wear. It can be restored to new by welding. There are many shops that can do that as well as re grind your existing cam to a better profile. May slant six folks trust Oregon Cam Grinding for that. A cam grind for you to consider is what Doug Dutra, a slant six guru developed. Google 'Doug Dutra RV-10 slant six cam'. You will get some info that way. Oregon Cam has their own version of the RV 10. I just google Doug Dutra / RV -10 cam and found this statement, attributed to Doug: "The RV10/295 RDP is designed for a 1bbl engine with compression ratios (8.4 to 9.0) and to have smooth idle with strong off idle and mid-range power."
An upgrade to an HEI ignition to do away with the points should also be considered.
And lastly on this list, be sure to service and clean the oil pressure relief valve in the oil pump. Again, you can google a few words like 'slant six oil pump oil pressure relief valve service and get more info.
The work you described initially would not be lost work, It would provide some increase in engine performance, particularly at low RPM's. The best news is that if you do decide that you want more performance, the internal work is done and you will only be swapping the intake manifold and carb.