welcome - the most common one is Caliber II 50’s. 10" wide and for a single motor setup work great, even a longer motor like your 6364. Dual motors you need to stick to 6354/6355’s.
Motor mounts are super common for Caliber’s because the axle is “keyed” with a shape that helps prevent the mount from rotating like Paris and others which are round. Square w/ an arch on top basically.
There are several mounts available. Enertion, DIYes have some. @Shogu12 has one too that looks like Enertions. @korryh has a great adjustable one too (i have a few of his).
Tons of options for Caliber’s. Several for Paris too, but beware rotation challenges. I hated my ADS mounts - PITA.