I have now completed course 101 on SU carbs, and know that they are not to be feared! Simple carb to rebuild, only if needed. But very hard to get air cleaners on and off! I found an extra set also to rebuild.
Found out that the dizzy gear on my distributor was 180 degrees out on the 1958 with the 1967 MGB engine in it. Go figure, Tried to time it and it keep coming up 180 out! So just switch plug wires for time being, The big flat screw holding the dist. dizzy gear in, will not come out to turn dizzy gear 180 degrees to make it point at #1 cylinder when #1 cyl. is at tdc.