100fires,

Welcome to Stovebolt.com

I have put a few 261s into 1954 Chevrolet trucks.

The place to start is to ID your engine: find and post all these codes and we can start directing information/links as appropriate for the year.

The few topics that are dependent upon years are:
- location of water pump
- water pump (cooling system) hose diameters to radiator
- 6v/12v flywheel/starter
- front motor mount location/configuration
- carburetor/PCV/linkage
- oil-gauge sender

There will also be other considerations dependent upon staying 1954 6-volt or converting to 12v.