We can make you poly mounts any height you want, within reason of course.

 

if you want more suspention travel, lowering the subframe is a horrible idea, the one thing that bottoms out first is the sub frame. i would lower the lower control arm mounting points. or remake steel lower control arms that are longer. i say steel cuz i wouldn't trust my alum welding just yet, but i got steel in the bag.

adding longer bolts and spacers is far from the safest, or in the terms of good handling..
far from desirable feel,. ultimately you are going to end up with play between the sub frame and the body that lows for flex and movment. can you see why a moving subframe is a bad idea??

 

for most home garage were welding is not an option..(sucks for you) you could make the lower control arm longer by making an extension at the ball joint as the s4's are bolt on. you would just have to cut and drill some thing steel plate. and then get a longer strut assembly. then you'll probably need longer brake lines and slot most parts so they can be adjust at the alignment shop( i do 10-20 alignments a week on every make/model)

just a foot note, i found that you can adjust the caster on the rx8 without it affecting the toe or camber, which is phenomenal, as i could adjust my steering pull on the side of the road. or even on the fly with an actuator...

 

So luckily fc engine mounts aren't complicated, pretty much a hockey puck with a hole through it and a long bolt is all you need to make engine mounts
FC3s Poly Motor Mounts
If you purchased that engine mount or any other one like it, you could buy a bolt 1" longer than that and stock a bunch of washers if you really wanted to achieve the 1" taller engine mounts you desire.
So my guess is that you are raising the car at least 1" higher than stock. Off road rx7, Yeee Haaaaa! I don't know what you will be doing with the rear suspension though

 

That would be nice. I have a pineapple racing oil pan and that almost 1/4" flange the pass mount bolts to gave the engine an annoying tilt.

 

For the love of...

OK, so you are lowering the subframe. Ignoring the "WHY?!" then just make new mounts.

Cut some 3" aluminium pucks out of round bar to the size you want. Drill hole straight through for an M10 bolt. Buy bolt/threaded rod of appropriate length and bolt to car.

 

Aluminum engine mounts = race car points

 

Yeah, but I wonder how this person can consider changing the position of the subframe but not know how to make a set of solid mounts?!