Personally I've never been a fan of angled mounts. Seems to me they offer no advantage to vibration isolation, plus the mount is always in sheer under torque loads, just waiting to tear. The flat mounts like those at bellhousing are more stable.

Never could figure out why slanted mounts were used in the first place. I know they are designed to compensate for axial torque loads around crank radius to apply more power more directly but they ignore simple engine weight combining with torque loading.

I installed a hot 360 [not as hot as your Poly] in the Townie using stock LA mounts and it took only one major torque application event to RIP OUT ALL 4 AT ONCE! Only thing holding in the engine was the headers & exhaust!

With the Cummins installs one of the major ongoing headaches is motor mounts, thanks to high torque loads. The very best may fail and some of the cheaper stuff like those at the link may last for years. The original Lord Fluid-Lastic mounts may be best, but no room in a stock Swepty for such things with a V8.