General advice is to avoid lowering blocks.
Options are to either buy mid-eye or reverse-eye springs that will achieve lowering (but not an exact science as your existing springs may be sagged), or get a specialist to reset your existing springs (and maybe add a half or full leaf depending on their advice).
I did the latter on my 65FB about 10 years and got it done at Suspension City (used to be in North Melbourne but now in Pascoe Vale) -
https://www.suspensioncity.com.au/. Cost me about $440 back then, so would maybe be double now.
The benefit of the latter approach is they will get it sitting exactly how you want it, but with new springs its a bit of pot luck.
Shane