Solid lifter cam in a stock 289 will not do much for performance. The idea of a solid lifter can is to be able to increase hp by greatly increasing RPM. To turn a 289 you need ported heads or after markets, larger valves, new valve springs (to match the cam), 4 into 1 headers, high rise intake, 600 cfm holley carb and forged pistons.
A mild roller will increase power in combination with tri-y headers, with cross pipe and high rise intake. Only need about 500, 550 cfm carb.