You can't simply 'bore' an A14 out to 1600cc as it would require a bore size of 81.5mm to get 1606cc & that bore size is really a bridge too far as it represents an increase of 5.5mm over stock & the gap between end cylinders gets perilously thin at a 79mm bore size.
An 81mm bore size on an A14 yeilds 1587cc.

However, ..
By using an A15 crank, & a bore size of 79mm, the end result is 1607cc. By offseting the centerline of the end pairs of bores away from each other by a small amount, it is possible to get a gasket to seal satisfactorily & thereby have a 1600cc A14 engine.

Can an A15 be easily bored to 1600cc??

I have heard of people boring out A14's but not so much A15's??

The A14 & A15 cylinder blocks are dimentionally the same, so by fitting an A15 crank & pistons into an A14 block, what you get in practice is an A15 engine with an A14 engine number. The only significant differences between the two engines are the crank, pistons & oil pan. [It has bulges on one side to clear the longer stroke] The block deck height & the rods are the same for both engines.

By using Mazda pistons, you can bore an A15 to 79mm, which is pretty much the practical limit, & if you read the post before yours, you will see that this yeilds 1600cc. [plus a bit.] Just be aware that at this bore size, the gasket sealing area between the end pairs of cylinders is geting a bit thin & a smaller size is recomended for engines that are normally stripped only once per season or less.

Third term...

1st: 1971-1977 with sedan-type Stainless grille (B120 & B122)

2nd: 1978-1988 with coupe-style plastic grille but rectangular centre emblem (B122 & GB122)

3rd: 1989-1995 "square headlight" grille