You use a piece of black steel thick wall 1/2" steam pipe sawn to the correct length to correct for the missing cast iron manifolds and reuse all the stock parts. You will need to find a pipe fitter to cut you the pieces you need from scrap and the usual payment is a six pack of cold beer. They are most susceptible to this offer at about 11:30 in the morning (assumes a noon lunch break timed to the arrival of the roach coach).
Were I lived in Tampa we have lots of ship repair facilities so finding a pair of spacers was easy. Check the yellow pages for a union hall near you that can direct you to a worksite and give you the name of the foreman to authorize it.