Another newbie question. I'm trying to help get an 80s Specialized Sirrus ready for riding for a relative that has very limited range of motion. We know he can't make the reach to downtube shifters. So, we're thinking of taking a set of 2005 Ultegra brifters that we've got left over from another project and simply putting them on the current set up, which is Shimano 105 7 speed from the 80s. Is this possible? I'm thinking it simply means pulling off the DT shifters and current brake levers and replacing them with the Ultegras. Am I being too simplistic in this?