street cam for 360 magnum

cost on this swap is why i ask about hydraulic flat tappet cams, trying to keep the cost down. knowing the springs will need to be replaced as well as other parts, it pushes rollers way on up there. just figured while the intake and front cover were off id put something in there besides a broom handle. if i remeber right cam specs on the flattys are based on 1.5 rocker ratio and magnums are 1.6. so anything i choose will have more lift than advertised. how much lift can a stock long block handle before things get too close? what springs to use with magnum heads and flattys? what pushrod lenght? it will need enough vacumm for power brakes all help is really appreciated! mike t