Vacuum problems

[vestas1]

Hello, I have a 1987 Ford 460 all stock except for the cam, it is the biggest cam I can use with all stock internals, used the stock timming chain for a 87 460, was wondering if it would mess with the vacuum don't have enough vacuum for the brakes, should I use a timming set for a 1970 Ford 460, found on some forums that timming set could improve vacuum, any help is appreciated. Thank you all very much.