i wanted to start off by saying you clearly know nothing about the engine your working on but ill play nice,
consider a factory tbi cam, low lift, around 220/230 duration at .050 and an lsa around 112-114 is what any cam that will work decently needs to be at. thumpr isnt even a good cam choice for a carb, they sound ok, they idle for ****, have ****** power and torque curves, and my utmost favorite is produce barely any vacuum so your just left with a screaming death trap that doesnt run right and wont stop your truck worth a damn, as well as adding the fact that your cylinder heads wont take that cam, your intake will not breathe what that cam desires and your 95 trans will be toast without further modifcation as well. also forgot to add that im pretty sure your nowhere near the 9.5:1 CR the thumpr is gonna require
as far as it being roller or flat, take it apart and find out. TBI started in 87. theres reports of roller motors all the way back then and not the newer ones. its a crapshoot in the wind.
your "build" needs alot more thought. Or alot more steady studying on your part as well. then once your mechanicals are done when you decide to run a cam that large you need to start looking into tuning otherwise your truck will still do nothing even with the right parts.