M-1 Intake Manifold

I've run a Holley Strip Dominator, which is very similar overall, including a spreadbore pad. Some say it was basically copied my Mopar Performance. I wouldn't worry about welding it up even though application was race only with a lot more gear. converter, head flow, etc. I also ran a Canton 1" 4-hole tapered spacer. I tested a Weiand Stealth against it and it was about a tenth slower, even after optimizing the jetting. Your milder application may not see as much difference. But the M-1 single plane is a good intake. Focus on tuning the carb and don't use an open spacer. You already have a generous plenum and don't want to give up anything at the bottom.