If you don't have a vacuum leak, you'll be fine. But there's been a lot of trouble with the vacuum water valve, either failing or leaking. One of the T-bird suppliers, who's name unfortunately escapes me, told me they had a new supplier with better results. I think they were in Nevada, but not sure.
For years the T-bird suppliers sold a replacement, an inline valve in the heater hose, two clamps, and a cable that ran from the heater control lever to the valve, thru the hole the vacuum hose used in the firewall. It was a bit overpriced compared to making your own, if you buy a cable, and "wrap" the eyelets on the end.
I've had mixed results with those valves not really shutting off. I've got one inline, and the intake manifold fitting (or original vacuum valve) replaced with a 90 degree one with a shut off built in.
In the winter, I use the cable, but in the summer I shut it off at the manifold to stop the "leaking heat" from overwhelming the a/c.
I would imagine you could do something similar on pass car. Simple, cheap, and works. Obviously, it doesn't look stock.
http://www.macsautoparts.com/f...http://www.americanclassic.com...These are typical.
miker
55 bird, 32 cabrio F code
Kent, WA
Tucson, AZ