I'll do a 103 chain if I am completely resealing the top end, including lower cover. The chains are cheap and easy to install. The l/h guide is a easy break while doing a headgasket on a older engine and reguires you pull the lower cover anyway so....... I've not seen a 103 break a chain and the ratcheting tensioner seem to be bulletproof aswell.
Valve jobs on 103s are not uncommon nor are headgasket leaks from the r/r corner of the head. 103's do have a tendicy to mix oil into the coolant tho', something I've not seen a 104 do. I wont recomend a headgasket on a higer milage 103 (130k+) without recomending a valvejob at the same time. These guides wear.... period. Our base valvejob repair is about 950.00 and will go up a bit of the lower cover is resealed and all rail replaced with a new tensioner insert.
Fan bearing brackets are also a pretty common higher milage failure and aren't that expensive to add into a valvejob.
Project Smoker, '87 603 powered wagon
Hauler, 96 CTD can you say torque?
Toy 73 Cougar xr7 convertible
Acme Automotive Inc.