Well, I have finally been able to run some trains on the layout! I have had to "blast" some additional clearances out on curves at various locations when running my CP Selkirk and heavyweight passenger cars, with my hot wire soldering gun. All and all I'm happy to say the 2-10-4 will haul 4 MTH heavyweight cars up all the grades with minimal slipping. I built all my custom bridges with 1/4" mdf board so all track sub road bed is able to handle the weight of the trains without relying on the support of just the fastrack.
In response to Bruces query on the foam construction, this how I went about it.
First I purchased 2" and 3" foamboard in 4'x8' sheets. For the risers I ripped them in 7.5" widths on my tablesaw. With the blade fully extended I could not cut all the way thru so I would have to flip and turn the sheet around to cut all the way thru.
Once ripped into the appropriate width, I proceeded to cut the "slots" along one side only at approx 1 to 2" intervals.
Of course you need to adjust the blade depth of the cut so there is still atleast 3/4" of material left. This will allow the sheet to bend at whatever your desired radius is.
You may need to make the cuts closer together if you require tighter radius bends.
I need to state you should be very confident in using a table saw as it can be dangerous repetative work and a table saw is unforgiving if you are not cautious.
All track was laid out on 2" foamboard sheets which covered my 1/2" plywood table top. With the track laid out I traced out the upper routes with black marker. With the risers cut and easily bendable to curves I could now use white glue to affix them to the base foamboards.
I used 3" nails placed along the marked lines to hold the curves in place while the glue dried.
Hopefully this helps those who might want to try this method of construction as it is quite fast once you have all your risers precut.
One negative is that cutting the foamboard on a tablesaw is MESSY and it gets everywhere so have a shop vac handy lol.