Technical Wish bones

So I'll be looking into this in the morning, I'm putting together a dropped model A front axle, I have a 42 wishbone that was made to fit around the steering arms/tie rods, has anyone used these to avoid dropping spindle arms? Or won't it work?
I'll be splitting the wishbones .

 

Most times the spindle arms need to be bent down to clear the axle, before you even get to the wishbones. It’s rather tight there under the crotch of the drop.

 

Do you have any pics of these modded 42 bones?
D

 

But after looking closer I see where it fits over the axle it's thicker the the A wishbones so maybe I could mill them down otherwise I don't think the spring perch will be long enough.

 

Those might be the later factory curved bones. Some have used them but they aren’t without issues. Others don’t care for the look and, as you mention, clearance issues might differ from the straight ones.
I think you will likely have to use the perches from the bones you chose and add spacers to fit the bones snugly to the axle.
Don’t be afraid to collect extra parts or even use A parts. For example, I have decided to try to graft longer ‘35 bones to the wider A yoke to keep mine unsplit while moving the bones around the bell housing/engine. All one or the other doesn’t do it. Sometimes you have to combine.
I know some have done spring over using late bones but not sure which perches. Will likely be an issue for me as well.
D

 

The 42-48 wishbones fit on a 2-1/4" axle, which your A axle should be. Maybe need a really thin shim, but should fit OK. If you have a 32-36 axle, you will need a 1/4" spacer.

A stock A perch probably won't fit that wishbone because the bosses on the wishbone are thicker. Most aftermarket perches are longer for the lower shock mount to also attach, but I'm not sure if they would be long enough for a 42 wishbone plus a lower shock mount.

 

Unless the front of your chassis is extra low in relationship to the axle, I can't see any advantage in using the curved bones which end up mounted lower in the rear; straight bones usually end up at decent rear mount height on the frame and look right.

Just heat and bend the arms to clear the axle and bones, like it has been done since the old days.

Easiest fix for the perch bolt length problem on later bones is to mill the top down and re-taper the hole.

 

Look like '46-'48 bones

 

If you would rather use the long '42 (actually, '46-'48) pins, they have tapered holes on their tops. One of the early Ford parts houses has tapered studs to fit these, making shock hookups easier.
Or, install the old Superbell mounts underneath...