May just be a bad hose, I've done many ls swaps and have never had a issue with it swelling the hose.
And some of them got the valve for the hydroboost system which makes more pressure
Not that I do not believe you, but I swapped a hydroboost pump for a standard pump on a swap I did a few years ago to eliminate the failure prone rubber cap on the extra return line port. I never noticed a change in steering effort between the pumps. If the pressure was higher from the hydroboost pump it was not enough to notice with a stock 87 G20 saginaw box.
I am thinking it is more like a 30 year old rubber hose that has met the end of its life. As cheap as the hoses are it is well worth changing. Same goes for brake hoses. When I change hydraulic parts on a brake system, I do them all. Master cylinder, calipers, hoses and wheel cylinders. When you fix a leak somewhere in the system the added pressure tends to blow out other worn components. Cooling systems are the same way with old leaking hoses, radiators and water pumps. Change it all and do it once or keep fighting leaks every few days, weeks or months as the next weakest link fails. I have seen ac systems blow hoses apart as well when a weak or failed compressor is changed. The 35 year old ac discharge hose on my 1980 Corvette literally turned into a mass of tangled rubber with the sound of cannon going off under the hood instantly followed by a spray of lime green pag oil coating the windshield that looked like I had just driven through the predator shortly after I got the ac system working with a fresh compressor. I had installed a retrofit high pressure cut-off switch as well so it blew out under ~400 psi.
Rubber tends to dry rot and fail suddenly. Good reason not to keep tires older than 5 years old by the DOT numbers on your ride as well. Most blowouts I have seen are dry rotted old garbage.