Need help - T.B.I. vs. carb

[68gmcdually]

I am in the process of remounting my '68 LWB extend-a-cab on a 1992 GMC 3500 dually frame. The new chassis came with a 5.7 L on straight propane. Eliminated the propane and put it on my brother's 1990 GMC 1500 and decided to put his intake and gas tank on my truck. My dad is a serious die hard against Throttle Body Injection, says that it is too expensive/complicated to fix. I would like to hear from anyone out there who has "made the swap" from a carb. to a T.B.I. system. Also did you have any problems locating the computer in a A/C equipped cab. Thanks alot, this board has been such a great resource.