This is a real pain in the $%^ job and I cringed when you said you had to replace cowling. All I can say is search the topic in here and read all the threads. This little bit of rebuilding took me over a month and I settled for the last outcome as the best of all possible evils. Each truck is different and there are no good answers for your task, just keep tweaking until you're tweaked out. No rules. just results is what you want to keep in mind. I finally quit when one posted answer said that as a 30 year experienced rebuilder, he always showed his trucks with hood open. Holy cow!