Back in 2010, I had the dreaded hit a speed bump, engine dies Hatachi carb
problem. My solution was to go to the Weber Carb conversion kit. Mass of vacuum Plumbing, wiring and a ECU, all gone bye bye.
After receiving the kit, I could see during the mock up, that, yes it fits, but it has some
major air (Breathing) restrictions as is.
1st; the adaptor plate openings, were way larger than the openings in the intake manifold.
My solution, Hardware Hank'd a die grinder bit, Sharpied the new gasket outline onto the
carb base on the manifold, stuffed some small rags into the runners, had my sweetie run the shop vac as I opened it up with the electric drill. Just be careful, this aluminum is soft and disappears quickly !!
1st pix shows the end results, 2nd isn't the best, but I dug out the old spacer plate, and laid the new style gasket on top to show the size difference.