Honestly I don't think it's as big an issue as many will tell you. Yes the HGs will hold just fine running stock. Some claim they blow them running stock but see my first response. It's a cramped are to work in, you can pull the front apart if you wanted to and do the work.
If you run the...
The worst repair you MIGHT need would replacing the head gaskets. The work can be done with the cab/body on but may require more dis-assembly of other engine bay items like the heater core. It has been done several times over with the cab on by people in their own driveway.
Should you require new head gaskets pulling the cab is the quickest and easiest way to get to the motor. Most other repairs can be done "cab on" while removing all the accessories off the top of the motor.
All of these are VERY good points and excellent recommendations. You not going to convert those that are closed minded and not willing to hear your points.