Longer shocks won't do anything as far as actually lifting the load, they are designed to control wheel travel up & down.(unless they are air shocks)
If it was mine, I would take measurements before bar install, then hang it & take measurements to find out the difference in ride height, then just crank the T-bars until it's back up to stock, or a little greater in height.
An alaignment after you get it to where you want it is always good too.
Run it with the stock shocks to see how it handles, then decide if you want to replace them.If you do decide to change them, you can send them to me for free disposal.
BTW, today is discount day...so ya get my 2 cents worth for free.
Ldub