There are several others but most are too modern for me. Some overhead cams aluminum things. The 181 Mercruiser has a few more inches an 8 port head on some. There should be lots of them in boats in your area. Also check forklifts. After I get it going with the 153 I'll start building a '28 Chevy four so I can run in some of the old time race events if I live long enough.