coil overs on a 46?

I have a question,
I have a 46 ford sedan,that has a solid axle that i put P/s on.
The original spring had no arch at all so I got a new posies super slider with reversed eyes.but this spring is flat also.i put new monroe shocks on it,but the car bottoms out BAD,i have a small block in it,and I don't think it can weigh more than the flatty.
what do you think of a set of coilovers to replace the shocks with.am i barking up the wrong tree?
I'm willing to try this befor i go to IFS.
Can anyone help?
Thanks Russ