You can also fab one up - easiest fix is just buy a vented breather cap off the shelf and pop it on. The breather up to the carb was for emissions, so when you floor it and blow by pressure has to escape, those gases are re-burned into the carb.
Or get this one on EBAY (only 20 bucks, not mine)
https://www.ebay.com/i/292787746883?chn=ps