"close" is about the usual distance between the exhaust and the starter on any GM V8 .... that's why most every parts store carries exhaust shielding wrap ... it's excess heat on the starter/solenoid, a common problem, get some heat shielding and the problem will likely go away, regardless of what's worked for the last 25 years .... alternative is the physically smaller
high torque starter and/or the remote start solenoid Bart suggests as the
'Ford starter trick', high heat plays hell with electrical connections such as are in the solenoid
Bill