I'm by no means an expert here, but from what I gather, there isn't much clearance between the piston and head, so a loose glow plug tip could cause some havoc.
Also, if you have the engine out already, it may not be a huge project to take the heads off. You will may save yourself some aggravation actually, as once its in your jeep, it may be more difficult
2012 Chevy 2500HD ECSB, 6.0L gas, auto, 4x4, LT
2003 F450, 7.3L PSD, 6 spd stick, 2wd, dump truck
1983 GMC K2500 pickup - working on a Cummins 5.9L swap
1987 GMC K3500 Dump, 6.2L diesel, TH400 auto - project plow truck