I think the MP .528 might be a little too big for your engine combo. It had a little bit of a lope in my 470 so it would probably have a lot more lope in your 383.

I have a Racer Brown solid flat tappet that is a little bit smaller than the .528 cam. I used the Racer Brown solid in some dyno testing and it was a bit too small for my 470 but it would probably work in your 383. If you lived close by I'd let you try it out but Poland is a long way away!