Booster hitting valve covers. What to do?

I have a 360 in my '64 Barracuda. I've put the MP cast valve covers on and the brake booster hits them. I know I can put the stamped covers on but would like to run with the cast.
How can I fix this?
I've heard that there is an offset booster.
Is there one and what years am I to look for?
Thanks
Mark