what is needed to put a 305 TPI motor into a 85 SS and what things are most often over looked with this type of an engine swap?  what are some of the difficulties i might run into while replacing the engine?  I already have the wiring harnest and computer that came originaly with the TPI motor.  i would also like to know what other modifications i might take into concideration to make the 305 TPI motor work better or more convenient for the monte.

Structurally this is close to a bolt in, systems wise it's more complcated. Merging the electrical systems the speedo and emissions will potentially be the largest issues. You will need really good service manuals appropriate for the years and models of the engine and the car. That means Helms manuals which are expensive, but will save ever so much down stream frustration and cost.

I'd get copies of Mike Knell's books as they are a wealth of information you will need, it's 50 well spent bucks.

http://www.jagsthatrun.com/

Chevrolet S10 Truck V8 Conversion

Chevrolet TPI & TBI Engine Swapping

Bogie 

I HAVE A 86 THAT I DID THIS TO. I PURCHASED PAINLESS WIRING HARNESS, THINKING IT WAS BETTER THAN MAKING MY OWN, AND IT WAS IN MY CASE. HARNESS SIMPLE TO UNDERSTAND AND INSTALL. I USED MASS AIR FLOW DESIGNED FOR USE WITH LARGER CAM LATER ON. WITH MASS AIIR FLOW METER I NEEDED TRANS AM AIR INTAKE SYSTEM AND ALSO USED RADIATOR AND RADIATOR SUPPORT  BRACKETS FROM AN F-BODY (CAMARO/FIREBIRD).INCLUDING ELECTRIC FANS. FUEL TANK FROM 87 4.3 MONTE. USEING SAME FUEL SENDER FROM THAT TANK AND INSTALLING NEW PUMP FOR TPI SYSTEM. MADE NEW PRESSURE LINE AND USED ORIGINAL FUEL LINE FOR RETURN FUEL LINE TO TANK. COMPUTER FROM S10 PICKUP P/N 1227165 AND PROM FOR 88 CORVETTE. HAD TO RELOCATE BATTERY TO DRIVER SIDE, TRAY BOLTS INTO PLACE  NO DRILLING. USED CRIUSE CONTROL FROM F-BODY.RELOCATED VACUUM BALL AND CRIUSE TO BEHIND DRIVER HEAD LIGHT. INSTALLED SERPENTIN BELT SYSTEM FROM 91 CAPRICE. I DID ALOT OF EXTRA THINGS ON THIS CAR TRYING TO MAKE IT SEEM FACTORY. IT TOOK ME APPROX. MONTH AFTER WORK AND WEEKENDS TO DO THIS. HOPE THIS HELPS, AND GOOD LUCK. IF YOU HAVE ANY QUESTIONS YOU CAN E-MAIL ME AT tim_pam@msn.com

Need more info.   What year TPI is it?  If its the old Mass air flow system you should toss it and update to a speed density system.  This update would require a different engine computer and aftermarket (closed loop) wiring harness.  You will also need a high pressure electric fuel pump.  These items will cost approximately $600 to $700.  The MAF system was a good system,  but it was also GM's number one warranty item.  GM went to a speed density system on all TPI's beginning in 1990.  If you have a TPI (90-92),  than you harness (with some mods) and engine computer will do the trick,  but you will need to either purchase an aftermarket prom (computer chip) to get around the antitheft,  or acquire a signal generator which inputs the required signal to satisfy the antitheft requirements.