I practiced Zen for over a decade. Only much later did I read the suttas. And after reading the suttas, I belatedly realized that practicing Zen alone without ready access to a teacher is a bit like learning to drive a stick-shift car on the freeway by yourself.
The suttas (Early Buddhist Texts in particular) provide a vast, coherent, inclusive, accessible and gently progressive path of practice that really informs the practice of Zen. For example, I did this for ten years on my zabuton:
MN118:17.2: Just mindful, they breathe in. Mindful, they breathe out. When breathing in heavily they know: ‘I’m breathing in heavily.’ When breathing out heavily they know: ‘I’m breathing out heavily.’ When breathing in lightly they know: ‘I’m breathing in lightly.’ When breathing out lightly they know: ‘I’m breathing out lightly.’ They practice breathing in experiencing the whole body. They practice breathing out experiencing the whole body. They practice breathing in stilling the body’s motion. They practice breathing out stilling the body’s motion. They practice breathing in experiencing rapture. They practice breathing out experiencing rapture. They practice breathing in experiencing bliss. They practice breathing out experiencing bliss.
Everything that I read in the suttas aligns with my experience of Zen. I have found no contradictions. Indeed, one sutta in particular was particularly helpful to me in aligning the EBTs with Zen:
MN44:12.1: “But ma’am, what is immersion? What things are the foundations of immersion? What things are the prerequisites for immersion? What is the development of immersion?”
MN44:12.2: “Unification of the mind is immersion...
The EBT stratification of immersion (i.e., jhana's, form and formless dimensions, etc.) was also very helpful to me as a guide, and it revealed pitfalls to be wary of as well as approaches I had not yet practiced.
My roshi was a 6-hour plane flight away. He was an amazing teacher and I made some progress. For those without ready access to good teachers, there are suttas such as AN8.63 that provide instruction that can be read along with Zen scriptures:
AN8.63:1.2: “Sir, may the Buddha please teach me Dhamma in brief. When I’ve heard it, I’ll live alone, withdrawn, diligent, keen, and resolute.”