84 riviera flywheel is it the same diameter as 84 t-type?

[the wrath]

If it is different size what starter would I need?

 

[1KWIKSIX]

The turbo Buick flex plates are balanced / weighted for the heavier “turbo” pistons used in the LC2 or Hot Air motors .
Since these motors are externally balanced it would be a good idea to match balance your replacement to the original to keep vibrations to a minimum