To gain infinite lives:

POKE 7552,C9

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Just RETurn, instead of decreasing Lives by one:

7552	LD HL,7839	Decrease *Lives by one.
7555	DEC (HL)

For infinite fuel:

POKE 76AC,2A

POKE E86C,3A

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Fuel is held by 783C and 783D. This changes the following two instances where the fuel is decreased.

Altering where the decreased fuel is written back to Fuel:

76AA	SBC HL,DE
76AC	LD (783C),HL

To LoaD the value into HL instead of writing it to Fuel:

76AC	LD HL,(783C)

And similarly, altering:

E867	LD A,783D
E86A	SUB 08
E86C	LD (783D),A

For a similar outcome (LoaDing into A instead of writing to 783D:

E86C	LD A,(783D)