Welcome to the forum! A great first graft might be a whip or whip and tongue graft
Bud 118 or mm111 would likely do good for you to plant an entire 50 - 100 tree orchard again. Here is a large wholesaler.
You can always send wood to @39thparallel and have him custom graft the bench grafts for you or grow the trees out for you for a year or order a few rootstocks from him to practice grafting with or order a bunch of different orchard trees to grow in your new orchard. Apples are his area of expertise and not mine. His trees are inexpensive. He is a good friend of mine.
These are the entire apple trees ranging in price from $13.50 - $23 . They would ship out this spring if they are in stock.