I decided to convert my 289 Galaxie to a 4 barrel leaving my 2 barrell just rebuilt 3 months ago an autolite 2100 free and being i keep having problem after problem with my 63 comets 1 barrel I decided to convert it to 2 barrel. what spacer do I need to get for the conversion I see there are 2 sizes, also what else do i need to do or know when doing this conversion. Engine is basically stock 170 M/T