My 40b that I bought during the last $1/gallon sale measures 36 1/8" long x 16 7/8" tall x 18 1/4" deep. I believe the plastic trim around the bottom is ~0.5" wide. Thats all that would be in contact with your shelf.
I would verify the capacities of the shelf. I looked earlier at some of the shelves at lowes and some of them are more than sufficient. But keep in mind the full weight of the tank will be around the 500 lbs range.
Plan where the tank and shelf will be located within your house. Ground level vs upper level, floor joists direction, load bearing wall, etc. Make sure it is located in a safe location.
I plan on using an Eheim 2215, which I hope will be sufficient. I have not set it up yet, so cannot give you personal feedback on that yet. I'm not sure how they compare to Sunsun filters.
I've got a glass lid for mine and will be planning on either Finnex Ray 2 LED or 36" T5HO lighting. Have yet to decide which way to go.
Just a few things to consider.