430ex2 and 7d

+1 to YOGI

If the promaster really has a 'simple M' only Optical triger device (i.e. no SD nor S2 setting) - then it's 'either / or'.

You could use simple M only RadioF triggers driven either from the cam's hot-shoe or the cam's pc sync outlet (the latter could leave the built-in pop-up unit able to contribute - but set flash mode to M & disable 'wireless' in the cam's flash menus). Might lose a little below max sync speed here . . .

Or (deep breath) you could dumb down your 430Ex(either) by fitting a simple optical (Ex friendly) slave trigger device to its hot-shoe. Then, again, render your 7D pop-up into a pre-flash free state by setting Flash mode to M and disabling 'wireless'.