The 1998 motor/PCM is a bit different from the later ones. The computer is huge, for one thing. You can make it work, but it's easier to package the later ones. There's also a difference in the valve covers so you can't use the cool Edelbrock coil covers 
Given your choice, go for 2001-02. You get the LS6 intake manifold. A bit more power. But it's not a go/no go kind of difference.
Given the FM conversion kit, you'll also need:
- accessories (the F-body ones can be used if some of their mounts are modified, if memory serves)
- diff
- possibly an LS3 Corvette starter, I'm not sure of the dimensions of the F-body one
And a bunch of non-GM parts. Again, see http://flyinmiata.com/V8/costs.php.
I'm going to check on that oil pan in the next couple of days. I have guests at the moment but they leave tomorrow. I've had someone else inquire about it already.
Looks like there's another page. Thanks for that, interesting reading.
Great thread. I've been obsessing over a Miata swap for days now and this thread has a ton of simple baseline info. Should have know GMS would bring the goods.
I'll add this... You don't need to get an entire driveline. The T56 and the LS-block are compatible. Grab a T56 from darn near any LS vehicle, then get your LS from something else.
The main case of the T56 has remained basically unchanged since its inception. There are different gear combinations and fork/synchro changes, but the center case carries the same configuration from 1992-present. That means you can swap tailhousings, shifters, and front plates to make various configurations. I have a Viper TNET T56 on which I put a GM input shaft and front plate, and had a GM tailhousing bored out for the larger viper output shaft. I basically made a GM input and output on a Viper center section.
The same is true for the C5 and C6 transaxles. Its a standard T56 main case that happens to have a differential case on the back.
I had a camaro T56 behind a truck 5.3L in an S10. Mixing and matching is super easy with these.
mdshaw
New Reader
1/6/13 8:41 a.m.
And don't even consider a T5. I got so tired of replacing those after they go bad.
^ Was it a built T5? You can get gearsets that increase the torque capacity tremendously.
The astro A5 gearset seems to have great reviews and is rated for 500ft/lbs, for example.
Is anyone using TKO transmissions behind an LSx engine in these swaps?
