Since no one else has commented on this, I do believe there is a difference in the firewalls on the bigblock vs. smallblock . Similar to the high and low hump issues for 4wd vs. 2wd trans. covers. Sadly, I have one of each type suburban's, but It would take a bit of effort on my part to measure or get photos. Maybe do a search at the top. Anyone else want to chime in?
