Here's a picture of my 69 with tall valve covers, the hydroboost master, and a DSE Wiper motor. My problem before the change was with the wiper motor, I would have to remove it to take the driver's side cover off. The master was never an issue though, never it.
I switched to the hydraboost setup because I run a big solid roller cam and really didn't have enough vacuum to run the brakes. Hydraboost is awesome!!
I changed the wiper motor because I need to have access to adjust the rockers more often with the solid roller cam and I didn't want to scratch my newly painted firewall up during the wiper motor R&R.