Welcome!
For an '86, the 4-speed 200-4R is original equipment. Whether or not it's still there is another story.
Take a look from underneath at the pan and this should help identify which transmission the car has now.
If the engine is not original, I wouldn't waste a dime, or a single minute of my time on converting a regular 305 to a HO 305.
Even the HO 305's are incredibly disappointing.
All that money and effort is better off being put towards a healthy 350 to replace it.
For an '86, the 4-speed 200-4R is original equipment. Whether or not it's still there is another story.
Take a look from underneath at the pan and this should help identify which transmission the car has now.
![transpan.gif](https://cdn-0.gbodyforum.com/proxy.php?image=http%3A%2F%2Fwww.chevcarclubvic.org.au%2Ftechnical%2Fimages%2Ftranspan.gif&hash=5ccbc0cb7eee3bf04fa13ba22228d1cd)
If the engine is not original, I wouldn't waste a dime, or a single minute of my time on converting a regular 305 to a HO 305.
Even the HO 305's are incredibly disappointing.
All that money and effort is better off being put towards a healthy 350 to replace it.