I was a mechanic, high end assembler, and occasional salesperson at a Serotta dealer from @'88 to 2000. The quality of those bikes is impeccable, yours may have been custom ordered because the CSI (custom option lugged frames) were sometimes hybrids of fillet and lugged construction when needed to get the customer's needed geometry. Often the main triangle joints were what some builders call "bi-laminate"--one socket cut off the lug and replaced with a fillet. The builders who did that neat **** were Kelly Bedford and Dave Kirk. Lueky you!! You could lower the gearing by changing the crankset and leaving the rear shifting alone--the friction downtime shifter is omnivorous, it'll work with any crankset you want it to work with.