I have a 1972 Gibson 36 with twin Chrysler 225 slant six's. The previous owner installed some crap carter carbs that have been rigged beyond usefullness. I had some fuel problems eary on, but have since replaced entire fuel system. These carbs have been cleaned on 4 seperate occasions and each has been rebuilt twice. I have had enough. Am I stuck trying to find a pair of the original Carter carbs (Model #BBS3364S or BBD3390S), or is there a modern day substitution? Any suggestions would be appreciated.