I'm not sure what I 27 refers to. To get to the Poly from I-75 (we drive I-75 from Kentucky), we normally:
- Get off I-75 at the Reagan (formerly Florida) Turnpike at Wildwood, FL.
- Take the Western Beltway (429) toll road when you near Orlando
- Take the Western Way into WDW property. Once on WDW property follow signs to get to Magic Kingdom. You have to go through the MK parking gate to get to the Poly. Stay to the right, tell the parking attendant you're going to the Poly rather than MK, and they'll tell you to go straight toward the Poly rather than veer left with the other lanes that actually go into the MK parking lot (the TTC). You have one more left after this, on to 7 Seas Drive, and the Poly is on that street.
I'm not sure which specific area you need construction info on. I know of no major construction going on along the Reagan Turnpike, though I could be wrong.
ETA: if by I 27, you mean Highway 27, I'd avoid that as much as possible. That same highway goes through my town in Kentucky and all the way up to Michigan. It is infamous for 2 things: 1) getting stuck behind slow-moving farm vehicles in 2-lane rural areas and 2) having endless stoplights in urban and even suburban areas.