SB shaft mounted spring compressors

Has anyone had success in using this compressor from COMP Cams 5323 Shaft Mount Valve Spring Compressor?

I have CompCam 901-16 springs installed on my 340 J heads with 2.02's. I need to replace the seals with heads installed.

Is there a better tool out there that anyone might have experience with?

Tks
Hey. I make valve spring compressors for both, std 426 for $195and 426 hemi running Chevy style pushrods for $395. Go to YouTube and text in valve spring compressor 426 hemi. Both of these compressors work with any intake manifold and any valve spring. I can make you one but it won’t be cheap. $195+freight. Satisfaction guaranteed.