This Question is kind of vogue but I’ll try to answer best to my understanding (mostly from the comments)
You can either use the build in post types where the pros are : A built in Admin UI,
Easy queries wrapper, and built in table listing, but the cons, as far as i can tell is the unnecessary fields in the posts table.
Or you can use your custom table which will store just the fields you need but the cons here are that you will have to write your wrappers to working with it including creating your tables listing from (almost) scratch and create your own admin UI to manage and use the project records.
Sure the easy way would be to use the custom post type but I do understand the major problem it presents if you don’t have any use for most of the fields and you expect 100,000 of records (anything less shouldn’t be a problem or cause performance issues, just a big table in the database).
So i guess its up to you which way is better to go with.