I don't know who you are talking to but I have installed several of the aftermarket booster/master upgrades on TF trucks. I did the conversion on my 56 over 10 years ago with a kit from ABS in Orange, CA. I have a 3 speed OD trans and there are no clearance issues with the column shift rods or anything else. Brothers, CPP and many other suppliers have the kits as well.
I think there may be some issues with clearances on AD trucks, perhaps the person you contacted was mixed up on the year or series.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine