I replaced mine with a 261 I found through a dealer Parts Counter in San Diego. It was complete, a First series '55 and it was a little bit of work BUT it fit and it did have a lot more power. Later I went to multiple carburetion and sent the 848 head up to the Sissell's shop in West Covina. Then I added a cam kit and an HEI and it is still going strong after 18 years. I've never been disappointed and the money I saved took me and the better half to Australia for a month the following year.
Normbc9