Yeah that could be a problem
good luck with your repairs!
as far as heat range, i'd stick with stock until it proves to need to be changed. being a long reach gasket type plug, i just wonder who determined the Autolite 3923 to be correct to begin with?
i use this reverse engineering tool to find alternate plugs for various cars,
they also have heat range charts on the page. IIRC they say Autolite doesn't use a standard heat range code so it's hard to cross reference different types of plugs?