I pulled the SP-1 off my 53 and its for sale. It had had a process called performance coating done to it. It still looks sharp. I helicoiled one of the base plate bolt holes last time I swapped out the carb and if I were to reuse it I would do the rest. Not having problems I just think it would be a good idea. $300.00 plus shipping. Located in Tacoma Wa. 98444
newer versions have a turtle back type hump on the floor of the plenum to help fuel dispersment at lower rpm's.