I tend to plan and overplan... so this may not be for you.
First off, I like to match my driveline and wheel/tire pkg to fit my purposes.
Different trannys have different drive ratios. Some trannys siphon off more power than others. Are you going to be mainly highways, lots of city?
Here's the reason why. Every engine has a peak zone for torque, and another band for hp. You can use desktop dyno programs or the such to learn what your build should put out before it's even built.
There's calculators online you can mix the trans, the tire size, and a speed to find how many rpm the engine will turn at that mph. If you pick these so your choice of either torque or horsepower coincides with where your driving style and needs will be.
A package that's optimized responds quicker, and is the reason why some guys have a build and it feels sluggish and dog like driving around. Others have the same build and the butt dyno makes you say man this thing is awesome.
You've got a chance to pick and choose at the beginning what your goal is and build around that.
Now, you can pick and plan anything right now. Budget matters. Depending what your long term plans are, different things make sense.
You talk about needing driveshaft, etc... let's get basic. You may even want to think what rear end you want to run so you aren't having driveshaft cut and balanced multiple times.
1) Any idea based on what you have for an engine that you expect to have for horsepower?
2) is this just a fun for now toy, or a long term build and keep car?
3) and any plans long term, as in this is my engine for now but I already plan to save for something bigger down the road? (Sometimes, if the budget allows, it's cheaper to spend $700 instead of $500 now, that way you aren't replacing that piece in the next step of the build.)
