The spin on kits are dead easy to fit, I had a cannister engine and swapped it over, depends on the brand some you have to remove your bypass valve fitted at the top of your cannister - bolted to the block this was the style that I got and some you re-use your bypass adaptor to attach the new unit. If you get one that doesnt use a bypass filter you have to use spin on filters that come with inbuilt bypass in them
Hope this helps
Steve