It would help us a lot if we knew the engine you have. So I recommend you create a signature, as explained in the Bullnose Forum/Forum FAQ's. That way our answers can be more accurate.
However, I'm going to guess that you have a Windsor. And I think that line goes across the back of the engine and bolts onto the back of the heads. If I'm right you can unbolt it and then insert
short 5/8-11 bolts with a copper washer under the head to seal it. And by "short" I'm talking about about 1/2" long as the threads in the head aren't very deep. Plus, you can't get a very long bolt between the head and the firewall.
Gary, AKA "Gary fellow":
Profile
Dad's: '81 F150 Ranger XLT 4x4: Down for restomod: Full-roller "stroked 351M" w/Trick Flow heads & intake, EEC-V SEFI/E4OD/3.50 gears w/Kevlar clutches
Blue: 2015 F150 Platinum 4x4 SuperCrew wearing Blue Jeans & sporting a 3.5L EB & Max Tow
Big Blue: 1985 F250HD 4x4: 460/ZF5/3.55's, D60 w/Ox locker & 10.25 Sterling/Trutrac, Blue Top & Borgeson, & EEC-V MAF/SEFI