At Merlin Cycles the following 7 items total $515:
1. Shimano 105-R7000 crankset (50/34, 172.5 mm)
2. Shimano 105 FD-R7000 front derailleur (braze on)
3. Shimano 105 RD-R7000-SS rear derailleur: GS version $6 more
4. Shimano 105 CS-R7000 (11-28 or 11-32)
5. Shimano 105 ST-R7000 STI levers
6. Shimano Ultegra CN-HG701 chain (105 chain not in stock)
You may also want to upgrade the BB (Ultegra SM-BBR60); there is no 105 specific BB. Don't forget to include the cost of shift cables and housings to replace the existing worn ones.