"Get the smaller one, the 600
"Get the smaller one, the 600 MARINE carb. You'll need to find a 12 volt source that is ON with the ignition is ON to operate the chokes. Also, your flame arrestors will be too small in diameter to fit these carbs. Being a Cheapskate, I enlarged mine with a pencil grinder until it fit, but 'normal' people spring for new ones. THe throttle linkage works fine, but you'll need to drill and tap the body of the carb,, in front, for a vacuum fitting to operate the PVC valve--easier than it sounds. Use an 1/8 NPT pipe fitting with a 3/8 hose barb on the other end.
Jeff"