Valve spring recommendation

Gents,

I have a mild 318 with stock heads - hydraulic gear. It's about 9.2:1 compression. I have a repop MP .444 lift 340 spec purple shaft cam. The car will probably max out a 6,000 RPM.

I need a slightly stiffer spring for the cam and wanted some recommendations. I bought a great set of mild Comp springs years ago but lost the number....

Thanks guys

Nick