Toilet replacement surprise: need to install new closet flange+pipe

My home (built 1985) has an original toilet on the second floor, so I decided to purchase a shiny new HET to replace it. So after I get everything together I unbolt the old toilet, wondering why it has four bolts holding it down--two on the floor, and to against the wall. (I figure most of you are cringing already.) I lift the bowl off and set it on the side, and look down to discover a solid floor underneath...no closet flange! After scratching my head for about ten seconds, I realize it is on the wall!
I decided I still want to put the new HET in, so I need to put a new flange into the floor. There is a joist between the old flange and the new location (and my 2x8 joists run the full length of the structure), so I need to run a 3" pipe 5 feet until I have access to vertical space. But I need to make a relatively sharp turn straight down, and vent straight up...is a Sani-Tee allowed for this?
I have some other changes I would like to make involving my DWV (lowering the kitchen sink drain, and redoing some weirdness in the basement).
I made a drawing of my proposed work. 3" and 2" are the only sizes used. My county defers plumbing to the WSSC (sanitary commission), and they use IPC (with amendments). They allow the owner to work on 10% of the plumbing without a permit, so I'm doing each fixture/floor as a separate project (with a month break between each).
I would appreciate any feedback/criticism/suggestions, as this is my first project of this size.

Satoshi

As you point out, this is your first project of this size. As a devout DIYer, I appreciate that you are trying to save some expense, but I would suggest that you should hire a professional to do the plumber portion. Done wrong and you could have a toilet that clogged regularly. I think you will be time and money ahead.

The drawings look nice.
If I were plumbing that in Seattle, I would be adding a vent to the piping in the basement for the first floor toilet, and connecting the vent 42" above that floor.
Right now, the upper waste is dropping down on the toilet wasteline from above, and that can siphon water from the bowl of the toilet.

The toilet can run out six feet to the flange from the vent in UPC

Someone that plumbs for IPC will know more about you local code.

Thank you Terry,
I've learned a lot reading through the many posts on your site, and I did my best to apply what I learned.
As you suspected, the basement piping did have a major siphon problem. The previous owner put that in with a wet vent through the lav...which was connected directly to a 2" vertical pipe with no trap at all! So I put a trap on it going into a tee, and I put an AAV six inches above the tee. This took care of the siphoning issue for now. At the time I put it in, I didn't know what the DFU rating meant, and had no idea how much overkill a 160 DFU AAV was! At least I won't ever have to worry that it's undersized.
This powder room doesn't seem to have any way to get vertical access for a real vent (and not enough vertical space below for an island vent), so it seems I am stuck using an AAV. Not having any problems with it, and I don't see any prohibitions against it in the local amendments to IPC, so it doesn't seem to be an issue. I plan to redo this room, but only after I completely finish my 2F bathroom project. I will update as that project approaches in a few months.
My thanks goest to you and all the other participants in this forum for all your knowledge and experience.
Satoshi