what engine should i put into my 97 firebird   i was thinking of a ls1 v8 what do you think  

i was wondering if anyone new how i could find out how rare of an engine i have
it is a 68' 428 casting #9792968 on the side of the block, its stamped GME.
its also a 4 bolt block and also has an armasteel crank.  i've only found 1 article about this engine in 20 years , it's supposed to be a ram air VI tunnel port  

This is my take on you idea:

I have had many friends with tired LT1's look at a suitable replacement motor after being forced to rebuild the LT1. The majority of them went back to the LT1. The reason for this is the benefits of the LS1 weren't worth the trouble for them. You can build a high-power LT1 on a reasonable budget. You already have the block and the car is already wired up for the LT1.

If you were to go with an LS1, you would have to find a motor to begin your build with. You may get lucky and find someone local who has one for sale, otherwise you are left to online ordering. Once you have the new or used engine, you have to wire it up. The 4L60E is controlled by the computer, so you have to keep the LT1 PCM that controls the transmission, the new LS1 engine requires the use of an LS1 PCM, so you have to have the two work together. I am fairly certain that the manual tranny cars don't have this issue, but don't take my word for it.

To be honest, the LT1 is a great engine. You can build it to handle some serious power, and they also nail down some good gas mileage. The biggest issue with them would be the opti-spark. There are now a few LS1-style coil pack conversions on the market, so you can get rid of the opti.