Around 6 hours 42 minutes to beat. That doesnt include having to replay the game since the USA Rom crashed at the end. I recommend playing this ROM.
In this video I break down all the strategies I used, including no starting power ups at most checkpoints. Checkpoint to checkpoint gameplay without power ups is rare in videos for these games, so that should be helpful. Not having any weapons really changes how you have to navigate each area.
For this tutorial I only show lives where progress was made, such as getting to a stage checkpoint. All other deaths are edited out. This shows the way the game works and the checkpoint system.
Non-commentary, longer version of playthrough shown here:
2