Reported speech uncertainty

Question

Can you help me with these?

Which of them are correct or sound more natural? How far into the sentence does the reported speech go- I feel like if I transform everything it changes the meaning and the time reference- past instead of the present.

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I miss you.

1. I'd lie if I said I didn't miss you

2. I'd lie if I said I don't miss you.

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He's not performing up to par.

1. I'd lie if I said he was performing up to par.

2. I'd lie if I said he is performing up to par.

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What if I want it to mean this:

He's been performing up to par. (Some backshifting should take place, right?)

1.I'd lie if I said he'd been performing up to par. (turning present perfect in past perfect)

2. I'd lie if I said he's been performing up to par.

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How about backshifting and tense agreement in general?

For instance:

"What are you gonna do tough guy?" "I was thinking of slapping you around till you cried/ till you cry."

Answer 1

Note that we usually say "I'd be lying if..."

Either of your options is can be heard, but the past tense is preferred. It can be read as an irrealis supporting the conditional, meaning that it's not actually the past. Compare to these expressions that are hypothetical rather than past:

If I had a million dollars, I would...

If I were king, I would...

You'll notice that your sentences essentially invert this structure.

That said, by using another tense, such as the present, you can remove any ambiguity.

I'd be lying if I said I didn't love you.
_{Realis past or irrealis present}

I'd be lying if I said never loved you.
_{Realis past only, but scope is different}

I'd be lying if I said I don't love you.
_{Realis present only, but may be frowned on by some}

This also applies to compound tenses:

I'd be lying if I said I wasn't going to marry you.
_{Are those plans still on or not?!}

I'd be lying if I said I'm not going to marry you.
_{The plans are still on, but may be frowned on for the tense mismatch}